Add short command line switches for convenience

[nitrocode]

Fixes #93

$ itermocil
usage: itermocil [options] <layout>

Process a teamocil file natively in iTerm2 (i.e. without tmux).

positional arguments:
  layout         the layout name you wish to process

optional arguments:
  -h, --help     show this help message and exit
  --here, -H     run in the current terminal
  --edit, -e     edit file in $EDITOR if set, otherwise open in GUI
  --show, -s     show the layout instead of executing it
  --layout, -L   specify a layout file rather looking in the ~/.teamocil
  --list, -l     show the available layouts in ~/teamocil
  --version, -v  show iTermocil version
  --debug, -d    output the iTerm Applescript instead of executing it