Did some bug fixes in PassiveShield.lua and ActivatableShield.lua.  Added splash art for shop and modified one of them (ActivatableShield.png, PassiveShield.png, and NRGRegen.jpg). Added in splash art for Passive and Activatable Shields in MenuEquip.lua.  Added Passive and Activatable Shield into Shop.lua.  Changed the isActivatable check to fit more cases in Passive.lua.  Also threw in a brightened up sprite of our ship that can be used when getting hit.