Implement the idle protocol

It allows clients such as swayidle and chat applications to monitor user
idle time.

simplify make clean

update make clean

layer shell initial attempt

Merge branch 'master' into 31-independents-mouse-focus

make XWayland support optional

xwayland: unmanaged (dropdown menu) support

warn but don't error on unused function

sacrifice 24 lines to suckless style :)

turn on some warnings

move config.h to config.def.h

make Makefile a bit more my style

Start with tinywl

Add a config.h into which configurables can be moved.