All of the monitor discovery logic can be implemented with Qt. This
change removes all the x11 implementations in favor of Qt and removes a
fair amount of platform specific code.

Allows manipulating and modifying the front-end via plugins.

This is to prevent confusion both when prefixing commits and when
reading the directory structure for the first time.

This allows installing the architecture independent data outside the
prefix, for example on a multiarch layout where the prefix is
/usr/{host-triplet}.

Closes jp9000/obs-studio#552

Implements transitions, and introduces "Studio Mode" which allows live
editing of the same or different scenes while preserving what's
currently being displayed.

Studio Mode offers a number of new features:
  - The ability to edit different scenes or the same scene without
    modifying what's currently being displayed (of course)

  - The ability to set up "quick transitions" with a desired transition
    and duration that can be assigned hotkeys

  - The option to create full copies of all sources in the program scene
    to allow editing of source properties of the same scene live without
    modifying the output, or (by default) just use references.  (Note
    however that certain sources cannot be duplicated, such as capture
    sources, media sources, and device sources)

  - Swap Mode (enabled by default) which swaps the program scene with
    the preview scene when a transition completes

Currently, only non-configurable transitions (transitions without
properties) are listed, and the only transitions available as of this
writing are fade and cut.  In future versions more transitions will be
added, such as swipe, stingers, and many other various sort of
transitions, and the UI will support being able to add/configure/remove
those sort of configurable transitions.

When you assign a menu to a normal QPushButton, it becomes a button that
only allows you to have a menu.  This class lets you click the button
and have a menu at the same time.

(Non-compiling commit: windowless-context branch)

This makes it so that OBSQTDisplay now uses/controls an obs_display
object directly (rather than having the owner have to associate an
OBSDisplay with it).  It was separated before because the main window
for the basic UI would was using the "main preview" stuff before the
windowless context and had to be handled differently, so you couldn't
just associate an obs_display object with OBSQTDisplay, meaning that all
"secondary" previews such as properties/filters/etc had to handle the
obs_display alone, which caused a lot of needlessly duplicated code.

Also adds a DisplayCreated signal to allow owners to be able to add
callbacks and such on creation of the actual obs_display context.

The properties window UI file has no point at this time.  It's just a
window with a widget inside of it.

Adds setting profiles to the basic user interface.  For each profile, a
subdirectory for the profile will be created in
[config_dir]/obs-studio/basic/profiles which will contain the settings
data for each profile.

Adds scene collections to the menu bar, which allows you to duplicate,
rename, remove, or add clean new scene collections.

Scene files are now stored in ./obs-studio/basic/scenes directory with
filesystem-safe names.

These functions are designed to manually delete item widgets within
other widgets to prevent ->deleteLater from being called on them.  This
prevents the item widgets from being stuck in the event queue, and
prevents references to things like sources from being stuck in the event
queue along with them if they're used in the item widget's class or
functions.

Qt5Network has been replaced by libcurl.

The RemoteTextThread class is a QThread that is used to get text
remotely in a separate thread with libcurl.  This is intended to replace
the Qt5Network classes because of their dependency on OpenSSL, which we
can't distribute.

OBSHotkeyEdit is similar to QKeySequenceEdit, except less terribad on OSX, while
OBSHotkeyWidget provides a container that automagically encapsulates multiple
bindings per hotkey

OBSHotkeyLabel in combination with OBSHotkeyWidget provides mechanisms for
dealing with hotkey pairs (see upcoming usage in window-basic-settings.cpp)

When this class is used in conjunction with a QSlider control, allows
direct setting of the slider handle position when clicking in an area
other than the slider handle.  The default QSlider handle behavior is to
step towards clicked position.

Adds an icon to the executable file so the executable no longer shows up
without an icon.

This allows viewing a source, scene, or the main preview in a fullscreen
window.

Adds ComboBoxes for selecting format and audio/video
codecs. The ComboBoxes also show only valid codec
combinations for a particular container format.

The FocusList subclass of QListWidget emits a GotFocus signal when it
gets focus -- used for the filters window to know when a specific filter
list gets focus.

This is used to allow the user to temporarily disable sources/filters.

For each item in the list box, it displays a visibility checkbox (with
eye icon) that the user can click to disable/re-enable sources or
filters.

I did not end up using the Qt::ItemIsUserCheckable flag with the list
items for a few reasons:

- We could not style the checkbox indicator without qss screwing up
  other parts of the list widget style on certain operating systems

- We could not get the icon to properly invert on active selection like
  the text does on mac/linux, which made it look strange

- Clicking the checkbox too fast would cause it to signal a double-click
  on the icon, opening the properties for a source in the source list

This checkbox gives an 'eye' icon that indicates whether something is
visible or not.  The color of the icon is influenced by the current
style's foreground color.

To accommodate multiple types of outputs, there has to be some level of
abstraction.  The BasicOutputHandler structure will give us a way that
we can switch between different output configurations.

Because libobs-opengl is a public library, it's customary to have SONAME
embedded in the library file.  Also remove the prefix override and
remove the prefixing "lib" from the output name.  This also requires us
to pass the library file name to dlopen invocations.

The default behavior of QListWidget is to allow double clicks of any
mouse button, but in certain situations/usage cases this can cause
undesirable results.  As an example: when double-clicking with the right
mouse button on an item in the sources list box, it will open up both
the properties window and the context menu.  Not pretty at all.

This subclass filters out double clicks for any mouse button other than
the left mouse button to fix this issue.

The regular scroll area can expand horizontally, but the problem with
this is that sometimes there are controls within it that expand way too
big.

For example, the properties window for window capture can have a list of
windows where the titles of the windows are really really long, and it
causes the properties to extend way too far to the right, making the
window look really unusual.

Another example are the volume controls in the main window that can
expand way to the right if the name of a source is really long, causing
the volume control to stretch way too far to the right, making the
volume controls difficult to use when that happens.

So this just makes it so it sets the maximum width of a scroll area's
internal widget to the actual width of the scroll area, preventing it
from going off the side of the scroll area.

This crash report dialog is mostly just for the windows crash handling
code.  If a crash occurs, the user will be able to view the crash report
and post it on the forums or give it to a developer for debugging
purposes.

This dialog gives options such as increasing audio past 100%, forcing
the audio of a source to mono, and setting the audio sync offset of a
source (which was an oft-requested feature)

OBS Sparkle feeds have two extensions to vanilla Sparkle feeds:
- There can be two kinds of items per feed: (zipped) .app and .mpkg
  via <ce:packageType>app|mpkg</ce:packageType> (default is mpkg)
- Feed items can be disabled via <ce:deployed>false</ce:deployed>; these
  items will not be considered for updates unless
  "[General] UpdateToUndeployed=1" is set the global config

Unlike other Sparkle implementations the FeedURL cannot be updated via user
preferences because we support multiple app packages with the same package
identifier but different FeedURL settings on the same machine