Refactor and extend TR types

[lahm86]

The main goal here is to get a step ahead of the next round of IO refactoring. The plan there is to have things such as models, entities and static meshes linked directly to type enums rather than using just numbers. This will eventually shift the specifics to the IO - so for example, TR2Entity has TypeID as a short but TRModel has it as a uint - these will become TR2Type in both cases and the necessary casting handled during IO instead of repeatedly throughout the solution.

Sorry this is another big one. It may be best going through commit-by-commit - here is a summary of the changes:

• Each game now has a complete type enum and namespaces for each changed to TRLevelControl.Model to avoid using bloat everywhere
• Explicit values have been assigned to each enum entry to make lookup easier
• The enums have been renamed from TRXEntities to TRXType - this makes the difference clear between TRXEntity and its type
• The type utility classes have been tidied up to match. No utility classes yet for 4/5 - this can be done when it's time to randomize those games
• TRGE DLLs updated as they make use of weapon types in each game