improved error handling, fix international style on european maps, fix error in theme manager

Bugfix Update:

I just uploaded an update that improves the error handling of BT. It will open an alert when the BuildingThemes.xml got corrupted, so you know what to do.

Also, this update removes the international buildings from the european theme on european maps (thanks for Glowstronium for the report)

Also, the error in theme manager (Dictionary key error) is now hopefully resolved.

moo!

added snowfall buildings + support for environment-restricted buildings. Added support for clones in theme mods.

Trying to fix some issues related to policy panel

hotfix for desktop crashes and other errors

Update: Now compatible with the new version of 81 Tiles (by BloodyPenguin).

Revert to prev version.

Fix a NullReferenceException

• update for patch 1.2.2-f2
  
• district theme configuration is now saved in the city save file. no more extra xml save files!
  
• hide DLC buildings for players who do not own the DLC
  
• Show levels (1, 2) for specialisations in theme manager
  
• Better error handling and display

fix cloning feature