Support for Wolfenstein 3D and Spear of Destiny

Game

Add support for vehicles #30
Add support for multi-guns
Add support for custom wreck objects and bullets (allows respawning actors on death)
Add support for custom actor death animation
Add option to skip debrief menu
Fix game freeze when returning to game after leaving it paused for a while
Fix duplicate missions in level select
Improve performance by adding max particle limit
Improve level select menu with max items limit
Improve game start menu by disabling continue option after campaign complete

Editor

Fix loading a campaign with less missions showing a blank mission #670
Add per-mission option to persist weapons (can reset weapons on certain missions)
Change map shortcut key to tab