v4 changes/additions

- Heretic support

- New weapons: Pipebomb, Silenced Mac-10's, Chainsaw

- Improved kick sequence

- Slightly changed shotguns visual recoil

- Changed menu sounds (taken from Compendium)

- Buffed Sawed-off

- Alt-fire for pulse rifle

- Custom explosive barrel

- Changed titlepic and interpic

- Footsteps

- Bob style change

- New HUD (for screen size 11)

- Alt-fire for fists

- MFG is now replaced with the BFG

- New player sprites