new function to notify keyboard enter

sort client.h functions

prevent an infinite loop if try to use focusmon() with all monitors disabled

don't try to set monitor for clients in createmon()

this is done in updatemons()

set monitor for clients that don't have one in updatemons()

only if selmon is enabled and the clients are mapped

set monitor for clients that don't have one on monitor creation

don't respect size hints for fullscreen clients

Fixes: #292

change type of c->bw: int -> unsigned int

reorder isfullscreen in Client definition

initialize to zero the box used in commitnotify()

handle client_from_wlr_surface() receiving a subsurface

fix crash when setting a custom mode

rework outputmgrapplyortest()

first disable requested monitors, then enable and/or change mode, x and y, etc.
This is mostly what sway does

2200: let's use this wisely

Looks like [suckless-dev] was right about one thing.

fix dist target

use `git describe` to generate version

check client_from_wlr_surface() returning NULL in urgent()

fix #281

fix segfault if parent->mon is unset

use the layer surface to create popups

make sure we do not create a double fullscreen_bg

and also make sure we do not destroy it if it does not exist
Fixes: #274