GLOBAL:
 * options : different types of tiles ?
 * background image + more animations
 * multiplayers highscore (increment scores for successive games)
 * key profiles (?)
 * autopause if focus is lost (cf kmines)
 * set the keyboard repeat rate (possible ?)
 * use KGame


KNOWN BUGS:
 * occasional crash in multiplayer wizard / with keybinding changes
 * infinite loop with out-of-bound call to GArray::at
   sometimes when creating several boards (human vs AI/human).
