tmux: renumber windows automatically
tmux: renumber windows automatically

Most of my window switching is done using `prefix ^a` (ie. the
`last-window` command), so the ability to jump to a specific window
using a number is less valuable than having the numbers grouped close
together (where accuracy is higher).

Signed-off-by: Wincent Colaiuta <c76ac2e9cd86441713c7dfae92c451f3e6d17fdc@wincent.com>

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent