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.

Right now, information about global audio sources is stored in both
scene files and in the config.  These must be separated; there's no need
to store them in both when they can just be stored in the scenes file.

This allows snprintf to be used in any file in the UI.

Checks for removals while enumerating, which allows one to be able to
remove a source in the enumeration.

This allows config file values to defer to their defaults instead of
being null.

Allows swapping the internal data of two ConfigFile objects.

Adds a function to copy a file.  On unix-based systems, manually copies
the data with fopen/fread/fwrite/fclose.

Adds a function to remove a directory.

Allows moving/renaming of files.

Fortunately this didn't actually leak memory since the function was
never called

System timestamps were being used instead of timestamps from the
audio/video input.  This would cause potential desync as well as
incremental buffering when using devices with the blackmagic video
source.  Using the timestamps direct from the SDK itself fixes those
issues, and causes audio/video to play back properly and in sync.

UI: Add Audio bitrate

CoreAudio AAC encoder is now available for both AAC-LC and HE-AAC.
Added some Audio bitrate settings for lower bitrate region.

When using e.g. a color correction filter on any source and changing
any value (with slider enabled, e.g. contrast) to -0.10 the value would
get cycle between -0.07/-0.08 at some point when using the up arrow; it
would also get stuck on -0.69.

For the other direction, when starting from e.g. -0.02 the value would
jump from 0.05 to -0.08 when pressing the down arrow.

Problem was reported at https://obsproject.com/forum/threads/32450

Allow cmake variables to be used to specify include directories, and
allow DepsPath or DepsPath32/64 to be used to specify dependency
locations.

Not ignoring these signals doesn't seem to break anything, but it
shouldn't be necessary to process them either

Workaround taken from <http://stackoverflow.com/a/30291775>,
potentially relevant Qt bug:
<https://bugreports.qt.io/browse/QTBUG-45365>

The empty implementation for the QDataStream operators is necessary to fix
a Qt assertion: "QVariant::save: unable to save type
'std::vector<std::shared_ptr<OBSSignal> >' (type id: 1036)."

It doesn't seem like a full implementation of the stream operators would be
useful since the signal registration is very specific to the interaction
between the scenes and sources list, i.e. in case the scenes list ever accepts
scenes from sources (not 'obs_source's) other than itself (non InternalMove
drag&drop?) it would have to register those scenes with the libobs core which
should trigger the normal signal registration

This minimal implementation should be enough to drag&drop scenes between UI
elements in the same process in the future

This minimal implementation should be enough to drag&drop scenes between UI
elements in the same process in the future

Also ensure only a single source is selected if it's an update from
libobs

This should reduce the chances of any deleteLater objects holding strong
references into the libobs core getting stuck in the Qt event queue

This introduces the OBSSignals data role, which will be used to store
signal handlers in stock Qt objects

This filter simply modifies the volume of the signal as a convenient way
of modifying the volume before other filters, or amplify the volume
without having to mess with advanced audio properties.

This adds functions specific to audio math, which at the moment is just
converting to and from decibel and multiple.