Let people know that this plugin requires mplayer. Note that we don't
currently check for it in the plugin, but we should.

Create a custom delete operator that plays the delete sound.

NOTES:
* Doesn't do `dd`
* I just looked at the tcomment plugin source and realised that I should
  be using plugin mappings so these can be more easily overridden. Make
  a note to look into that.

Add Spencer's new Cantina audio files to the cantina list. The new audio
files are shorter individually (that's why there are more of them). This
makes it easier to play the Cantina song at faster or slower ranges of
tempos.

Each audio file is an 8th note.

Uncomment the space and delete mappings. Note that I had to remove count
support on the delete key because it's another one of those that was
giving me errors for that.

This way the sounds on scoll commands acutally work. They no longer
support counts :( and the <c-b> command for some reason needs to be
entered twice in order for it to work. Enable these for now just so we
can get the sounds but add FIXMEs so we know that these are borked.

Again had an issue with adding a count to one of the mappings, in this
case with redo. Leaving the mapping active except not supporting a
count. Hopefully we can figure out how to fix that.