Removed dimswitch script. I liked it but it has been utterly superseded
by styler; if wanting to switch light and dark I can just switch to
light or dark base16 theme and do not have to rely on alacritty config
file hacking through dimswitch (well, now just through styler, yay.)
exist script will print message to stdout even if it prints to notify,
this makes more sense since now passing a loudness factor just adds it
to the message, instead of replacing printed message with libnotify.
Added stow ignores to top-level files. Not entirely sure if it is
needed, but they were linked on my system and the change shouldn't hurt.
Renamed ifinstalled to exist, moved it into base shell module. It can be
called with just a command name to check for, or with an additional
libnotify urgency level (low, normal, critical).
If called with an urgency as the second argument, the user will be
notified of the missing command with the corresponding urgency.
