Don't send empty theme in config

- Restrict game config changes in special rooms - /unfix command

Experiment in adding a "boing" graphic for bouncing. It has no text right now (was thinking l10n) and colour is fixed.

Add rubber utility. Graphics are still incomplete. Also flag snow/ice in theme config.

Add missing gstCollision bug #725

fix issue #724: Bee sound never stops (underwater when timer is 0) also: instead of flowers add bubbles while underwater

string/typo fixes