Third time's the charm -- finally got Alacritty configured to a minimal
usable state. Font is displayed differently which will take some getting
used to.
Also adjusted the tmux keybindings, added in descriptions, and generally
just made things clearer. Apparently I was still using the default
bindings for switching panes and just mapping the iTerm2 shortcut to
it, so I brought those more in line with the cmd-<key> bindings for
easier translation.
