Removed most of hardcoded checks for fort level or for presence of fort/
citadel/castle buildings.
It is now possible to define which parts of town fortifications are
provided by town buildings
Configuration for H3-like fortifications is provided in
buildingsLibrary.json and will be used automatically by mods as long as
mods have buidings named "fort", "citadel" and "castle".
Alternatively, mods can separately define:
- hitpoints of walls (shared value for all sections)
- hitpoints of central, upper and lower towers (separate values)
- presence of moat
- shooters for each tower (separate values)
