[WIP] Explosions (and TNT)

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