implement handling key press event
* this will be used to capture binding keys later on
make sure we exit cleanly even if we have windows opened
tweaks to the settings dialog to support keybindins grabbing
some other minor tweaks to the look&feel
allow filelist close to succeed even if pynotify close() fails
update README to reference requirement to Keybinder
updated schema to allow storing global keys
Implemented global configurable key bindings to toggle next and previous wallpapers