Display desktop number with the pattern in window mode

This is merged from the original upstream at:
https://github.com/seanpringle/simpleswitcher/blob/master/simpleswitcher.c
Select the target desktop in non-i3_mode

Fixes https://github.com/DaveDavenport/rofi/issues/28

This is merged from the original upstream at:
https://github.com/seanpringle/simpleswitcher/blob/master/simpleswitcher.c
(including the TODO)
Make things behave nice again in i3.