Merge pull request #11 from Edward850/master

Updated MENUDEF
More crap to do
Fix Heavy Powersuits and Indestructible Stims not being handled
Fix outdated Demolition Ammo icons
Fixed Spider Mastermind Hell spawning issue
WHOOPS
Monster Defense was only working in steps of 100
Adjust EP and ammo drain to be nicer to the player
Rejigged the Agility formula. In other news, I'm a terrible person.
Make things a *bit* less wacky wheels
Tweak a LOT of the lights to be nicer
Added Demon Artifact for Collection missions
Fix resurrection with Arch-viles

Enemies will now keep their stats upon death. They will only give up their ID if
they somehow disappear, like a lost soul hitting the end of its' death animation
or Thing_Remove being nasty.

When a monster dies, it's flagged as NOXP and NODROPS so re-killing it will
yield nothing, therefore it's not possible to gimp missions or auras to give you
tons of credits or things like that.

This should hopefully work better now, but it needs testing.
Add feedback when you're affected by EP/ammo drain

Real sounds are currently pending, sorry.
...Except it wasn't working, whoops.
MM-12 was doing integer multiplication at the end

...so it only ever had three states: 1x, 2x, and 3x. It should be smoother now.
Did a bunch of crap to the Shield Booster and it's beam
Change how the BST-700 drops the shields to look better and toss the pickups further from the player
You can now use Quick EP even if Shop Anywhere is disabled
Some better code for the shield boosters