Fixed a bug that could cause a crash when generating the first dungeon

I've updated the demo version to fix a bug that could cause the game to crash when generating the first dungeon. In browsers the message was as follows:

GwtApplication: exception: Unmatched value: BOUNTY_HUNTRESS 

(The name on the right could be different, it was depending on the random number generator).

It was caused by monsters of later dungeons not being fully implemented. Thanks @Azaet for reporting it on discord!

Also people reported that the browser version was a bit sluggish. Indeed input feedback is quite slow. I'll will be working on that very soon, I believe it's caused by too much opengl texture swapping.