This patch fixes a specific crash where if the user named a filter the
same name as an input source that already existed in the system, scene
item loading code could find the filter with the same name instead of
the source, and mistakenly use it as the scene item's source directly.
This would cause a crash when trying to render that filter as a regular
source.

Marking filters as private is a temporary and simple workaround to the
solution.  Filters are currently not meant to be found via the main
enumeration/search functions, which is a design flaw (lack of
consistency).  In future major API revisions of libobs, filters should
be reworked to act as sources, with the sources they filter as
sub-sources ideally.

Additionally, the concept of "private context objects" and "primary
lists of context objects" in the back-end should probably also be
removed, allowing the font-end (or optional separate API layers) to
control all primary lists of obs context objects.  These minor issues
that occur ultimately stem from API design flaws which need to be
corrected.

This crash happened when a filter was mistakenly used as a regular
source due to an unrelated bug in filter code and scene loading code.
The filter and the source it belongs to both had the same names, and the
source loading code found the filter and mistakenly used it as the
source instead of the actual source with the same name.

Fixes warnings with deprecated function av_free_packet (which was
replaced by av_packet_unref)

Fixes warnings with deprecated packet functions (av_free_packet and
av_dup packet, which were replaced by av_packet_unref and av_packet_ref
respectively)

This is to work around a Mesa issue that prevents copying
between RGB and RGBA textures. Other drivers seem to allow
this, even though it's technically not allowed by the GL
spec.

Closes jp9000/obs-studio#514

Closes jp9000/obs-studio#494

Allows the user to snap sources to the edges of other sources, on by
default.

Closes jp9000/obs-studio#530

Allows users to snap sources to the horizontal or vertical centers of
the screen.  Off by default.

Closes jp9000/obs-studio#528

Allows the user to disable snapping all together or control the snap
threshold.

Determines whether an obs object was created successfully.  If a plugin
that's used for a saved object is removed (third party plugins), its
data will become invalid, but the objects can often still be created for
the sake of preserving user settings, but sometimes these objects can
cause problems if they're actually used (such as using them for
transitions).

(Note: This commit also modified text-freetype2)

Prevents issues from being able to update files that may not be using
the current system encoding on windows.

Windows needs filenames to be processed as wide, while libobs operates
on UTF-8, so a windows-specific function is needed here.

Useful for two purposes:

1.) When many devices are hooked up to the system and used in separate
scenes, but only one device active at once is desired

2.) Allows users who are dependent on outputting audio to desktop to
disable that audio (via disabling that device) when the device isn't
being displayed

This error implies to the user that the server still thinks they're
logged in, but that apparently no longer happens (at least on Twitch).
If the error happens, it usually means that the key is invalid or that
there's some general server issue, so update the message to reflect
that.

Fix redundant specifiers and change specifiers to match Linux date
command.

Closes jp9000/obs-studio#531

The crop texture would not always render correctly because the
projection matrix had not been set.

Renders the scene item to a texture if crop is enabled; otherwise
renders directly.

Allows the ability to defer updating the item transform until all
functions have been executed.

Allows the user to specify custom formatting for their recording file
names with many formatting options, viewed via tooltip.  The options
have been added to the advanced settings section.

Closes jp9000/obs-studio#507

Maps specifiers and accepts ones that work across multiple OSes.

On some systems, depending on locale, the specifier may resolve to an
empty string or nothing.  GenerateSpecifiedFilename will avoid
conversion of the specifier if this happens, to help guard against this.

Closes jp9000/obs-studio#521

Closes jp9000/obs-studio#526

Add support for devices that can output in grayscale (Y800).

(Note: Also modified the obs-ffmpeg plugin module)

Allows the ability for frame data to pass 8-bit grayscale images (Y800
color format).

Closes jp9000/obs-studio#515

Sometimes the timer will be triggered twice in one request.  GIF files
can be rendered in wrong speed.

Closes jp9000/obs-studio#513

Closes jp9000/obs-studio#516

Certain older devices (such as the Decklink Duo and Quad) could not be
selected due to the fact that they rely on BMDDeckLinkTopologicalID for
their unique identifier rather than BMDDeckLinkPersistentID.

See http://forum.blackmagicdesign.com/viewtopic.php?f=12&t=33967

Closes jp9000/obs-studio#517

text-freetype2: Use GS_A8 type glyphs texture