Reorganised vehicle load code and scripts

Moved all primary variables and functions relating to vehicles to
"/scripts/Vehicles/Core.pwn" the file "/scripts/Vehicles/Spawn.pwn" now
only contains code related to loading vehicle data files and spawning
them in the world, all the generation code for vehicle data is now
inside "Core.pwn".

Rewritten the load function for vehicles, it no longer requires an index
list of files due to the FileManager plugin (stole the code from
Maps.pwn filterscript!)

Removed specific loading of static vehicles for trains, put a check into
CreateNewVehicle that uses AddStaticVehicle when required, the two
trains in the map (tram and goods train both in SF) have been moved into
the SF vehicles file.

The folder "scriptfiles" will be updated soon.