This adds a interact button to the source toolbar. It is only
shown when source is interactable.

The source toolbar allows quick and easy access to properties and
filers, and shows common properties/features of a source type.  For
example, when you select a media source, VLC source, or the slideshow
source, you'll get media controls to control playback of the media.  If
you select a text source you can edit the font, color, or text if
applicable.  Or if you select a capture source, you can select the
display/window/etc to capture for that source.

If the source toolbar is not desired and is viewed as taking up valuable
space in the window, it can be disabled via the view menu.
Co-authored-by: NClayton Groeneveld <claytong1214@gmail.com>
Co-authored-by: NJim <obs.jim@gmail.com>

The files on disk are lower-case but QSS refrences them in
upper-case. Windows doesn't report errors as the platform isn't case
sensitive. Error messages are generated and icons not to render on
case sensitive platforms such as Linux and Mac

- Add pop-out and close svg icons
- Update all dark themes qss with the new icons

Co-authored-by: NJim <obs.jim@gmail.com>

Allows the ability to save replays with a button rather than with the
keyboard if desired.

Closes obsproject/obs-studio#1954

Adds an option to the right click menu in the scenes widget to switch
modes. When in regular list mode, it'll let you select grid mode, and in
grid mode, it'll let you select list mode. Grid mode changes the scenes
widget to have a grid of buttons for scenes rather than a list, much
like XSplit.

(This modifies UI, libobs, deps/obs-scripting, various cmake files)

Found using:
`codespell -q 3 -S *.ini,./UI/data/locale,./deps/w32-pthreads -L aci,dur,iff,mut,numer,uint`

Adds support for pausing recordings.  When settings are eligible for
recordings, a pause button will appear next to the recording button.  If
the settings are not eligible, it will warn the user in the output
settings that they cannot pause recordings if those settings are used.

This fixes a pixelated font on high-DPI

- Selected but unfocused Source colour
- Scenes font
- Padding when editing Source name

This changes all of the icons from png to svg. With svgs, scaling is
unlimited. With the svgs, the issue of the @ symbols with the Windows
updater is no longer an issue.

I changed the colors of the icons to a light gray (#d2d2d2), in the
dark themes, because I thought they looked better with this color.

The mute, unmute, plus, minus, up, down and expand icons are from the
Feather Icons set. https://feathericons.com/

The visibility icon is from the Octicons set. https://octicons.github.com/

The locked and unlocked icons are from the Open Iconic set.
https://github.com/iconic/open-iconic

- Fixes Q_PROPERTY macro syntax
- Removes excessive notification declaration and slot
- Removes unneeded dynamic property
- Improves Themes versatility

Fixes an issue when it's hard to perform drag-by-mouse move of the
scrollbar while handle is at corner and has minimum size.

Info: the handle minimum size styled as 20px, while add/sub-line is
14px, thus only 6px left for mouse drag when handle resides at corner.
While handle styled to cover whole bar including, subcontrol elements,
it is better to remove the hidden subcontrols completely.

Fixes an issue when it was hard to drag by mouse the scroll handle in
Dark theme if scroll handle size is close to full size
(https://obsproject.com/mantis/view.php?id=466) or close to minimal
size.

Also, the mouse pointer was misaligned to the scroll handle when
moving: the scroll handle always moves faster than mouse pointer itself
and finishes first.

This changes the remux dialog to support a collection of input/output
pairs, presented as a QTableView.  Standard Qt icons are used to
indicate the state of each entry during a remux operation.  Drag/drop
support is added to populate the list quickly.  Both Dark and Rachni
themes are updated to make QTableView look reasonable.

Relevant text is added in the localization files.

Closes obsproject/obs-studio#1153

In the Dark theme, disabled UI elements had text that was too close in
color to enabled UI elements. This commit switches them to use the
"light" palette color instead of the "lighter" palette color.

Adds the ability to set the current palette for the program via adding
"OBSTheme" objects to the qss files.  The values for the OBSTheme object
are the values used by QPalette::ColorRole.

Modifying the global palette allows the ability to easily/quickly look
up application theme colors (especially if you would like to use them
for QML), as well as the ability to fix the hyperlink color issue.  (On
dark themes, links would still be dark blue, causing them to be
difficult to see)

The decay rate of the audio meters can now be selected in the audio
settings.  The values are:

- "Fast"   (OBS default, 40 dB / 1.7s)
- "Medium" (Type I PPM,  20 dB / 1.7s)
- "Slow"   (Type II PPM, 24 dB / 2.8s)

Closes jp9000/obs-studio#1143