Allowed for grabbing of keys for AirWM

Took a while before I realized the exact method to grab the keys with
the xlib library. Found usage at:
https://github.com/knarf-se/yawm.js/blob/f498e1ca76e4bb12aa14801eadd180486444edfc/yawm.js
and consulted `node-x11/lib/corereqs.js`.  Added all the event masks
given in the x11-lib. The eventmasks not needed can be uncommented
later.

Signed-off-by: Martin Jorn Rogalla <martin@martinrogalla.com>