Split chapter creation from audio splitting.

Audio splitting can now use either vfr.py as before, or TheFluff's old split_aud.pl
upon which vfr was based. split_aud doesn't make chapters at all though, so if vfr
isn't set it shouldn't even attempt to make them.
Updated to reflect how it's used now-ish, though these are not useful defaults or anything so this is kind of stupid.
Add Encode Versions

Add the ability to automatically insert EPNUMvVERSION in case a new encode
is needed. This is probably most useful for SD encodes following a script
update, but not exclusively.

Also this hunk of the code adds the ability to mux mp4 chapters into a SD
encode, as they've been generated for months but not actually used anywhere.
This requires a patched x264 such as JEEB's, so it's best not to generate
them at all if you don't have it.

Assuming I didn't mess up the --patch hunk selection, this should also
add functionality for default template names so you don't need to type
them every time, though honestly I bat scripted that so long ago I'd
never notice.
Out_template change

There's a format change to how out_template handles scripts to not need
[[OutDir]]. That's been committed for a while actually, but the example
(which isn't an example, but was a real-use version) wasn't updated.
mkvtoolnix update

A while ago, mkvtoolnix changed track numbering to be zero indexed
instead of one indexed, so this updates to work with new versions.

If you have an old version, comment out the new command and uncomment
the old one I guess. Could probably make this safe/user friendly but
eh.

Also, if your chapters have multiple named editions, and a tags file
was generated, this will mux them. If a tags file does not exist, it
will just omit the parameter, because I finally got less lazy about
that fairly simple if os.exists() wrapper.