Revert "FFMpeg: Fix uninitialized AVFrame, which led to crashes with recent version of libav and ffmpeg"

This reverts commit 84903fce2548688ac47cb8b2d98e5876e3e55142.
Merge pull request #162 from teleshoes/fix_ffmpeg

Revert 84903fc: "FFMpeg: Fix uninitialized AVFrame"
added a script to download and compile deps for debian
add a script to compile stepmania+ffmpeg on debian
compile: explicit chdir to repo dir
compile: chdir out of _build/
compile: add a simple installer
compile: do not use _build/ dir
compile: fix error message
compile: include src in install dir
compile: remove ffmpeg compilation, bundled libav works nicely
compile: add symlink to ~/.stepmania-5/Songs to install dir