linux-capture: Add OBS_SOURCE_DO_NOT_DUPLICATE to window capture sources

It seems that it is not possible to create multiple OpenGL textures
for the same window. When sources are duplicated in studio mode this
causes window capture sources to become black. The
OBS_SOURCE_DO_NOT_DUPLICATE flag prevents that this happens.

test: Fix compiler warnings about incompatible pointer type

Update Restream.io ingests list and set recommended keyframe interval to
2.

(Commit edited and formatted by Jim: Fixed commit message)

Closes jp9000/obs-studio#565

Whether buffer size is visible is determined by the value of the "Use
buffer size" property (the "use_bufsize" setting).

(Commit edited and formatted by Jim: separated this code from the
previous commit, and gave it a proper commit message)

Closes jp9000/obs-studio#567

This is why macros should be used for settings strings.

(Commit edited and formatted by Jim: separated this code from the
following commit, and gave it a proper commit message)

Closes jp9000/obs-studio#567

vlc-video: Enable building the plugin on Linux

This reverts commit 4c505e70.

Reverting this for the time being due to issues with quakelive.  This
will be more thoroughly tested and hopefully added again.

How this was replicated:
- Create new VLC video source
- Add video in its properties
- Press cancel on the properties dialog to reset the settings

The scene check prevents the ability to remove scene items that have
been detached from their scene, which can happen when scenes are used as
scene items and the scene is deleted elsewhere.

When the crop filter was changed to a crop/pad filter, the sampler state
was changed to use a transparent border for the U/V addressing mode.
However, what was not realized at the time was that the scroll filter
also shared the crop effect file, and the scroll filter depended on the
old sampler state (wrap u/v).

This fixes the issue by simply setting a u/v wrap sampler state in the
scroll filter.

Add new Ukranian translations

Makes it so third-party plugins are stored in system-local specific data
directories (except on linux, which will still use user-local data
directories for the time being)

Adds C++ functions for getting system-local specific data directories
rather than user-specific data directories

Allows getting the system-local program data path.  Typically:

Windows:  C:\ProgramData
Mac:      /Library/Application Support
Linux:    /usr/local/share

When configuring file formatting settings in advanced, allow the ability
to specify formatted directories.

For example, "%CCYY-%MM/%DD %hh-%mm-%ss"

would make the year and month a subdirectory, then the
day/hour/minute/seconds as the file name.  January 21st 2121 at 4pm
would end up being:

"21 04-00-00.mp4" in the subdirectory "2121-01".

Commit 8932bd39 attempted to fix the starting position when the program
started up inside of a monitor that no longer exists, but it was
incorrectly assumed that it would cause the program to automatically
center its position.  Instead it set its position to {0,0}, which is a
really awkward position.

This fixes that commit and ensures the window starts up centered to the
primary display when its saved starting position is invalid.

Tested using FTL (steam): SwapBuffers ultimately calls wgl_swap_buffers
causing an additional copy which just isn't necessary

This also causes game capture to sometimes capture overlays even when
not intended

This reverts commit bd70e73c.

Turns out the commit was due to a miscommunication -- the commit it was
fixing actually worked fine, and this fix was unnecessary.

If window capture fails to find a window with a matching title, search
for a window with the same window class additionally as a backup.

Replaces the third part of the internal window string with the class
name instead of the program path due to the fact that the program path
rarely seemed to work.

The active_refs and show_refs variable would only increment/decrement
their children if their values were 1 and 0, which means that in the
case of scenes within scenes, sub-sources of scenes within scenes would
end up having the wrong ref values.

This reverts commit a6d7cbf2.

Due to users inquiring what the "buffering" option does, it would be
best to have a bit more details in its wording as to its function.

Allows adding scenes as scene items.  Note that you will not be able to
add scenes if it detects infinite recursion (i.e. adding scene A to
scene B, then adding scene B to scene A), in that case it will just fail
to create the scene item.

Allows rendering scenes as scene items without off-screen sub-source of
the scene popping out on the sides.

Scenes have special duplication handling, so make it internally call
obs_scene_duplicate instead.