Bombs!

- Added 'vulnerable' switch for monsters as well as player. No visual
indicator yes but this will replace weapon 'potency' to determine
whether a monster can be harmed by an attack.
- Added bombs as a secondary inventory item
- Added bombs to sidebar
- Added bomb pickup, with functions to increase/decrease # you have
- Can place bombs if you have bombs
- Bombs flicker for 3/4 of a second, then flicker faster for 1 second,
then explode for 500 ms
- Bombs hurt everything in their radius a single time
- Fixed a bug so monsters killed by bombs still have loot drops
- Bombs destroy bushes
- Fixed some SFX issues in firefox
- Increased volume of player's "ow" so it can be heard over explosion
sound