syphon: Remove references to game capture

A bit of a hack, but this is one of the more common errors that users
are encountering, so showing useful information will help cut down on
the number of support issues.

We don't read cached offsets any more, so it makes little sense to write
them on every startup.

Increase the buffer size to read the response in one call if possible,
and cause an error condition with log message if the offsets string is
empty.

- Enable b-pyramid frames
- Adjust packet priority to avoid dropping referencable B frames

Closes obsproject/obs-studio#1520

Closes obsproject/obs-studio#1625

Fixes the narration reading (for the blind) for items in the sources
list; previously they would not be read due to the new custom model.
This issue is solved by returning the name of item in the form of a
QVariant of a QString returned from the QAbstractItemModel::data virtual
function when the Qt::AccessibleTextRole role is used.

Prevents audio from cutting out below the -1000 offset (approximate)
threshold.

Reduces log file clutter by not logging certain warning messages that
were already safe/normal/expected failures.

Although log files are saved with the date in the name of the log file,
it's also nice to be able to see it inside the log file itself,
especially when uploaded to a text service.

UI: Save scene collection before export

Update all UI at default values when clicks "Defaults" button in the
source Properties.

This fixes mantis issue 1242.

Closes obsproject/obs-studio#1592

Some of the format of the Json changed (adding alt_names), so update the
format version to prevent it from being used with older versions.

libobs: Allow const argument in obs_set_cmdline_args

libobs: Fix Windows Game Mode detection on newer Windows 10 versions

Decklink: only use RGBA when using keyer

obs-qsv11: Log errors on init

rtmp-services: Update Chaturbate POPs

Build on PPC64LE using x86 Intrinsic Compat Shims

UI: Support fractional scaling

Decklink: Keyer Support

libobs: Fix utf-8 bom is not properly skipped

obs-filters: Add limiter filter

Adds optional alternate functions to allow passing the encoder type_data
to reduce code duplication.

Closes obsproject/obs-studio#1541

libobs: Fix crash when pixel or vertex shader are missing

linux-capture: XCompCap now chooses glXFBConfigs based on window depth

obs_set_cmdline_args copies the arguments passed to it. This means that
the array passed will never require it to be modified.

Add Discord badge to README

libobs: Fix circlebuf_pop_back returning front

On Linux the preview widget scaling uses only the integer part of the
scale. This results in a partially non-repainting window that looks
buggy and annoying.