Shift Okular to DOC workspace
Remove M-v keybinding
Assign M-v to adjust volume
Merge branch 'develop'
Remove comments
Add set_wallpaper.sh

It's necessary to reset the wallpaper after rotating screen, or
restarting xmonad. Moving the commands out of 'xinitrc' to a standalone
file, will be easily called by 'rotate_screen.sh', 'restart_xmonad', or
even assign a key to it.
Remove worldmap.jpg
Add greenfield.jpg
Add exec_xmonad.sh
Make scripts executable
Add wallpaper resetting in restart script
Merge branch 'fea/move_wallpapersetting_out'