[skip appveyor]

rtmp-services: Update maximum bitrate for Twitch

Updated max 3.5 to 6. See https://help.twitch.tv/customer/portal/articles/1253460-broadcast-requirements#Broadcast%20Requirements

rtmp-services: Update ingest list for Restream.io

Same issue as 77ceb97f corrected but for POST responses.

CI: Use ccache to speed up the build

Speeds up recompilation by caching previous compilations and detecting
when the same compilation is being done again. [skip appveyor]

This would cause people to download the 64bit files when they were on
the 32bit version of windows, even though those files aren't meant to be
installed.

The file could deflate infinitely until hard drive space ran out.

The updater would return HTTP 400 on an empty json array upload for the
patch manifest.

The GetTempPath and GetTempFileName functions weren't being used
correctly, GetTempFileName always create a temporary file, and was
creating a temporary file in the root directory of the hard drive
unintentionally.

EnumProcessModules may not work correctly cross-arch, so use
GetProcessImageFileName instead to ensure no issues in that case.

Used by the update module on windows.

To check to see if a file is locked, it must be opened for writing, not
reading.

CI: OSX - enable sparkle

CI: OSX - Brew install speexdsp

Fixes another 100% CPU spin bug, improves low latency mode, fixes some
crashes on stopping stream due to race conditions.

The LGP issue is caused by the device drivers returning two or more
packets in a single segment of audio data.  This fixes it by detecting
that and decoding subsequent packets.

When the FFmpeg audio decoder returns, it returns how many bytes of data
was decoded.  To have it decode multiple packets in a single segment,
just subtract the return value from the expected size, and if that size
is still larger than zero, then there are more packets in the segment to
decode.  Otherwise, stop.

This reverts commit 32f60d07.

VST: Fix crash when OBS is set to mono

VST: Fix save / load of plugin state. More interface options.