revert shift lock handling (broke uppercase letters)

revert shift lock handling (broke uppercase letters)

With some layouts, this broke uppercase letters in your passwords.

I think that explicit shiftlock handling is unnecessary. X11 seems to do
it on its own. Here is what leads me to that conclusion:

  $ setxkbmap de
  $ xmodmap -e 'keycode 66 = Shift_Lock'
  $ xev

Now enter a character, say "a", then press CapsLk (which is now
Shift_Lock), then press "a" again. The event state is 0x1, thereby
undistinguishable from normal shift.