Add instruction for registering async filter
Minor cleanup
Specify landscape in android manifest, should fix the wrong orientation issues.
Merge pull request #1854 from unknownbrackets/audio-minor

Improve audio blocking and some sceAudio functions
Shader simplification: Flip skinning math around. Remove a temporary from the texcoord generation code. Update ffmpeg submodule pointer.
Correct sceVaudio NIDs.

May fix #1738.
Don't overlay Vaudio with multichannel.

It seems to share living space with Output2/SRC.
Correct some error codes and initi in Vaudio.

This makes Velocity at least play sound, hurray.