Improve Voxel Explosions

this shows how I thought about the whole explosion thing

* Adds the possibility to set the lifetime of a voxel explosion
* Adds the possibility to add a random fluctuation to the lifetime
* Makes ALL voxels spawn "explosions" with a lifetime of debrisLifetime
* Applies the force parameter to the particle spin as well
* Correctly spawns particles in exact place of destroyed voxel (fix)
* Removes enemies from HUD

Normal voxels spawn debris-explosions with random lifetime (rather long).
What we saw so far are "real" explosions (fire, boom) with more force and same lifetime for all voxels.