Minor changes
Script inheritance changes

* Added IScript
* Moved init code from ScriptManager to script classes
* Changed NpcShop to inherit from IScript
Renamed NpcShop to NpcShopScript

and moved it to the scripts.
Renamed BaseScript to GeneralScript

* Added NpcShop and BaseScript dummy classes for backwards compatibility
Follow up 7cd18710c31c4078f0e64cf2e155ffbd2d9f9acc
Added some script loading checks

* Added catching of ReflectionTypeLoadException.
* Added obsolescence check for BaseScript and NpcShop