plugin/auditory.vim: Play sounds using absolute path

Without this, the audio files wouldn't be able to play unless you were
cd'ed into the script's root directory. We want them to play no matter
where your pwd is.
plugin/auditory.vim: Mappings that didn't quite work

Add commented mappings that I've been trying to get working but that for
one reason or another haven't been able to figure out how to do so.