Code submissions have continually suffered from formatting
inconsistencies that constantly have to be addressed.  Using
clang-format simplifies this by making code formatting more consistent,
and allows automation of the code formatting so that maintainers can
focus more on the code itself instead of code formatting.

obs_audio_data* sent to compressor_filter_audio had audio->frames == 0.
The analyze_envelope was trying to access an array at index -1 in result
of that. Just return if no samples are provided.

This fixes Mantis issue: 1261

We're expecting a variable with double precision. Since we don't read
the value of these doubles with a particular precision, it can often
lead to unpredictable results where the value set isn't the one
intended due to the loss of precision from float->double conversion.

Closes jp9000/obs-studio#1188

Adds a sidechain (ducking) option to the compression filter.

Signed-off-by: NShaolin <admshao@gmail.com>

As recommended by cg2121, attack is increased to 500ms, and release is
increased to 1000ms.

Closes jp9000/obs-studio#799