Optimizations, changes, and bug fixes ahoy!

+ Redesigned the HUD: the HUD is now a-lingual and uses icons to refer to ammo types and health.  The font used for displaying ammo count and health is now also pixel perfect with the rest of the HUD design.

+ Added monster infighting: some enemies may now infight on occasion!  Mannequins have a 33% chance to infight with another enemy if attacked by them, and Masked have a 50% chance.  These values may change in the future.

+ Mannequins now have a death sound and an alert sound.

~ Increased rivetgun damage.

~ Updated fluid textures.

~ Optimized rendering and collision of level geometry.

~ Optimized many smaller performance-taxing things, such as torch props, item pickups, enemies, and probably many more.

~ Reduced revolver alt-fire/melee damage.

~ Fixed visual bugs with weapon pickups.

~ Fixed changelog viewer not working correctly.

~ Fixed weapons & ammo persisting after respawning or finishing a level.

~ Fixed a memory leak caused by player & entity damage.

~ Fixed teleporter/portal mesh using back-face culling.

~ Fixed lighting issues with key pickups.

~ Fixed time scale not resetting after level transition.

~ Fixed player being able to occasionally harm themselves using their own weapons.

- Removed player collision check from Dream Orbs.