[gnome-nibbles] (21 commits) ...Improve Controls labels.

[Arnaud B. <arnaudb src gnome org>]

Summary of changes:

  66b7e72... Add Speed panel. (*)
  8a5a9da... Clear Preferences dialog code. (*)
  ef57c30... Rework Preferences dialog. (*)
  afbf2a3... Clean ControlsGrid. (*)
  07316c4... Add translators comments. (*)
  6e32d09... Fix some warnings. (*)
  bbe9da5... Do not start game with uncontrollable worm. (*)
  590d4fe... Remove Preferences entry. (*)
  deebce0... Allow to set a key used by absent worm. (*)
  c79674b... Do not allow multiple worms to use same control. (*)
  d6fc697... Warn when a key is assigned to multiple controls. (*)
  7e6df96... Fix typos. (*)
  2555548... Remove CSS warnings. (*)
  52dea26... Remove unused signal. (*)
  19b1754... Avoid a textual repetition. (*)
  93d6cbf... Move UI files in ui folder. (*)
  7057e0b... Fix Preferences dialog background color. (*)
  518572f... Make a MessageDialog modal on the correct window. (*)
  1299e92... Disable back action on level ended. (*)
  16e470f... Translate "Number of players" screen. (*)
  b94b34e... Improve Controls labels. (*)

(*) This commit already existed in another branch; no separate mail sent