Now edit all resource files for a particular tool (vim/bash/etc)
at once, with a single alias.

Vim now uses focus-gained/focus-lost events to automatically turn
relative numbering on and off. Ideally, once I've taken over manual
control of this feature using <Leader>l, it should no longer use
the autocommands, but I don't know how to turn off autocommands.
(`augroup! RelativeFocus` doesn't seem to work.)
Added comment stating that I want vim to turn off focus-based relative
numbering autocommand once I've explicitly turned relatvie numbering on
or off; see previous commit