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