ATV-TW: a trait (and future ancillary) validator for RTW/M2TW

[Tamur]

@ Makanyane
Thanks! Exactly what I needed. I'll get that implemented as soon as possible, this morning if I can swing it.

@ rorarii
What would you want a building validator to do? I'm not much of an expert with the edb file. I'm assuming that you would need to validate that:

1. the building entries for each building match up with the "levels" enumeration
2. the "upgrades" property of each building matches with the levels enumeration
3. settlement_min entries give valid settlement levels
4. any "recruit" entries give valid dictionary entries from the edu file
5. "cost" and "construction" values are numerical
6. there are no entries in edb without corresponding entries in /text/export_buildings

Anything else that could cause a CTD?