Some clients try to set _NET_WM_STATE_FULLSCREEN even when the window is
already in fullscreen.
For example, c->oldstate was set two times in a raw and window would
then always be floating.
We must check that it's not the case before processing it.
(original patch modified with suggestion from Markus Teich
<markus.teich@stusta.mhn.de>)

important:
- drw_rect: didn't use w and h, change the dwm code accordingly.
- drw_text: text is NULL is not allowed, use drw_rect().

- signal: print error string.
- die: start message with lower-case (consistency).
- bump version to 2015.

dmenu uses Xft now (soon to be released).

"Limit the amount of updates when resizing or moving a window in floating
mode to 60 times per second. This makes resizing and moving alot smoother
and by limiting it it also uses alot less resources on my machine.

however renamed theme into scheme resp. Theme into ClrScheme

- idea is not supporting movemouse/resizemouse/togglefloating for fullscreen windows
- as fullscreen windows are broken anyways, they should only be adjusted by their own means