Open game in full screen; default word levels

The game now opens in full screen mode and can be exited by pressing
the escape key. I originally removed full screen mode because my son
was freezing the game and in full screen there was no way to exit
cleanly. But now he accidentally presses system keys which interrupt
game input when not in full screen. I never solved why the game would
freeze, but it has not happened in awhile.

I imported more words from Wikipedia's list of 1000 common words. I
also set default levels that are completely based on the length of the
word. This was done with
db.words.find().forEach(function(doc) {
doc['level'] = Math.max(0, doc['_id'].length - 3);
db.words.save(doc);
})

If you do not wish to have these defaults, you can reset the level with
db.words.update({}, {$set: {level: 0}}, {multi: true})
Merge remote-tracking branch 'origin/master'