[dev] [dwm] Patch to support WM_TAKE_FOCUS and InputHint

Hello,

I recently noticed that some applications were losing the input focus
in dwm, while it was properly maintained under other window managers
(ex. twm.) After some poking around, I discovered that dwm doesn't
handle the WM_TAKE_FOCUS atom or InputHint, as outlined in section
4.1.7 of the ICCCM. This causes some issues for clients which
implement any of the three non-passive input models, as they either
expect to receive WM_TAKE_FOCUS so that they may claim the focus
themselves, or may not expect to receive FocusIn events at all.

I've attached a patch to fix this issue - it only adds a total of 11
lines of source, and factors out logic from isprotodel(..) and
killclient(..) into a new function sendevent(..) which handles both
detecting protocol support and sending supported events.

Thanks,
Brendan MacDonell