Mob bugfixes

* Mobs no longer require constant line-of-sight to a player to remain
aggravated
* Fixed an ASSERT
* Fixed mobs jumping
* Fixed Idle state not properly using AI
+ Added FILE_IO_PREFIX to favicon loading
+ Implemented #563
Implemented pickup combining

* Fixes FS393
* Part of  #131
Attack() is no longer always called
Implemented fall damage for mobs

+ Implemented mobile fall damage
* Formatting fixes
+ Defined new Position->Integer macros