Added inventory/pickup type signalling end of list to allow for adding/removing pickups with less code changes
Added assetDefines include file for global/shared asset path definitions
Fixed default spritesheet constructor not adding a sprite to the list

Changed foxblock logo on boot
Added short comments about the purpose of several classes to the header file
Adjusted battle stage to look like mockup (WIP)

Changed inventory / item icons
Merge pull request #2 from foxblock/master

Minor style and visual changes