Fixes and balancing

[Taeir]

This pull request contains fixes and balancing measures.

• Fixed door collision lag (for real this time, tested and everything).
• Bombs picked up by the knight now explode after 10 seconds instead of 5.
• Explosions are now sized properly.
• Explosions now have a damage multiplier value in their constructor.
• For bombs, the damage sustained is approximately (maxrange - distance) * 0.25 hearts.
• For landmines, the damage is about 1 heart.
• Changed bomb explosion radius from 8 blocks to 6 blocks.
• Increased bunny spawn action cooldown from 15 seconds to 20 seconds
• Fixed walk sound sometimes stopping
• Fixed walk sound containing a lot of noise
• Normalized door open sound, so that you can actually hear it.
• Extended fuse sound for the longer bomb timer of the knight.
• Reduced walk sound volume.

[Geweldig]

Great, should be merged.

[Diocruel]

Well needed! Merging.