New weapon type: Flame thrower, smoke grenade, contaminated smoke

[teoman002]

Flame thrower

• weapon base is the grenade launcher
• fires death effect entities that interact with nearby walls
• death entities check if their environment contains zombies / humans
• field damage effect

Smoke related

• death entities randomly move through air and interact with walls
• they check if players are nearby and interact in some way if they touch the player.
• smoke can make players invisible if they stay in the smoke, feature for ninja
• contaminated smoke rapidly reduces life points from humans