* button-widget.[c], panel-widget.[ch] panel-marshal.lst:
Remove keyboard move functionality from ButtonWidget. It is now
necessary to be in Move mode before it is possible to move applets
using the keyboard.
Tab or Shift+Tab will move applet to next or previous panel.
Shift+arraow will push applet a small amount
Control+arrow will switch applet
Alt+arrow will free move an applet
Escape will exit Move mode