Simplify STL usage as requested by function comment.

UI/updater: Various updates

UI: Fix output icon size. Add padding to settings list items

UI: Fix transition A/B labels on macOS/Linux

Previously, if the video size in OBS was too big, the labels would not
render on macOS/Linux due to the labels not fitting inside the texture
in the freetype plugin. This change makes it so that there is a maximum
size for the label, rather than being solely based on video size.

This change also makes the labels look centered on macOS/Linux, as
unlike the GDI plugin on Windows, the freetype plugin aligns the bottom
of the text with the bottom of the source.

Twitch will now return a 403 HTTP error code if you attempt to query
your stream key when your Twitch account does not have two-factor
authentication enabled.  This handles it a bit better and displays an
appropriate error message for users so they know where to go to enable
it.

Allows the ability to use things such as links in warning dialogs,
optionally.  Disabled by default.

This can take a while on a hard drive since it hashes the entire OBS
installation, show a undetermined progress marquee to avoid users
thinking that the updater has frozen.

CI: Build CEF with OS X 10.11 target

CI: Fix travis test on OSX

UI: Revert Dark theme Scenes font change

This fixes a pixelated font on high-DPI

win-wasapi: Speaker enum fixes

Remove KSAUDIO_SPEAKER_2POINT1 because it is included in the Windows
SDK. (I'm guessing it wasn't before.)

Redefine 4POINT1 as KSAUDIO_SPEAKER_SURROUND|SPEAKER_LOW_FREQUENCY
instead of KSAUDIO_SPEAKER_QUAD|SPEAKER_LOW_FREQUENCY. See definitions:

FFmpeg 4.1: FL+FR+FC+LFE+BC
WASAPI QUAD: FL+FR+BL+BR (looks wrong)
WASAPI SURROUND: FL+FR+FC+BC
WASAPI LOW_FREQUENCY: LFE

Fixes "Toggle Preview" hotkeys from duplicating when profiles are
switched.  The hotkeys were not being unregistered.

libobs-d3d11: Bad indices in log output

GitHub: Add funding buttons

Fix bad logging for LogAdapterMonitors and LogD3DAdapters. Update
EnumD3DAdapters for consistency.

Normally, paired encoders are unpaired when they stop.  However, if the
pairing occurs before the encoders actually start, and the encoders
never actually end up starting, they are never unpaired, and that
pairing stays with them until the next time an output is started up
again.  That in turn can cause an output that uses one of the encoders
but not the other to not function correctly, and neither properly
"start" nor stop because the data is queued continually in the
interleaved packet array.

For example, let's say there are two outputs, two video encoders, and
one audio encoder.  This can be reproduced by using advanced output mode
and making the two outputs use separate video encoders while sharing
track 1's audio encoder.  If you start up the stream output first and it
fails to fully connect for whatever reason (bad server, bad stream key,
etc), then you start up the recording output, the recording output will
appear to be running, but will not stop when you hit "stop recording".
It will stay perpetually on "stopping recording" and will get stuck that
way.  This is because when the streaming output started, the streaming
output would initially pair video encoder A with audio encoder A before
the encoders actually fully started up (as the encoders do not fully
start up until a connection is successfully made), and when the
recording output starts up after that disconnection, audio encoder A
will wait for video encoder A rather than video encoder B because that
pairing was never actually cleared.

So, instead of pairing encoders when the output starts, wait until the
encoders themselves are being started and then pair the encoders at that
point in time.  This ensures that the encoders start up and will clear
their pairing when no longer in use.

UI: Fix issue where rec time left would show negative time

The recording time left timer was being called an unnecessary time,
in the stats constructor, when it should have only been started
when the recording starts.

libobs: Remove unreachable YUV decode paths

A previous refactoring to make DrawMatrix unnecessary has left behind
unreachable YUV conversions. Even if this code was somehow reachable,
DrawMatrix for YUV -> RGB doesn't exist anymore, so they would render
incorrectly anyway.

Minor cleanup

Variable was never used. Clean up both C++ and shader code.

Incoming texture is UNORM, so the value must already be saturated.

Lambda replacement was added, but old function was left behind.

Shuts down browser panels early to ensure that cookie data doesn't
necessarily get lost.

UI: Remove 5 file limit for drag & drop