Ctrl+hjkl to navigate windows

This one will conflict with joofsh's Ctrl+jk for pgup/pgdn, but I think
he'll like it.  (If not, he can use ... powers to bind the keys his own
way after this setting runs)
Bind similar window split keys to those of tmux

I'm getting away from [tux]+| and [tmux]+- for splits, because you can't
do ^w- and ^w| in vim, since those are already bound.

This is a harmless change from the defaults, since vim doesn't do
anything with ^w% or ^w".