[WIP] Explosions (and TNT)

This is WIP now, so I'd appreciate some feedback.

What works / what to do:

- create explosions and drop the related blocks [DONE]
- use the block's blaze resistance [TODO]
- setting near blocks in fire [DONE?]
- check whether they are flammable [TODO]
- damage nearby entities [TODO]
- detect and fire near TNT [TODO]
- send explosion sound [DONE]
- send explosion particles [TODO]