bugfix: happiness influence

The happness influence radius wasn't shown properly. Also, there was a
bug when removing a building, weird effects happended at the corners of
the happiness effect radius.
Bugfix: supplys + implemented supply radius

The initialization code for the supply algorithm used wrong coordinates.
Implemented upgrade system (#69)
Major improvements and bugfixes for upgradesystem
Various enhancements

Better cameracontrol, more tooltips, internal changes, better seperation
of cost and monthly cost, ...
Added shield (#78) + upgrade enhancements
Implemented adaptive street system
Added models for garbageyard upgrades
Buildings can now be rotated
Bugfixes (buildingrotation)

rotated buildings caused some problems
tweaks and fixes
New dataview button textures & bugfix

The texture of the citycenter did not show up on mouseover
Added unlock text & bugfix happiness

There were still problems with negative happiness influence in corners
around buildings.
Added model & texture for police (#10)
Added police upgrade models + bugfix .lang-file

The language files were not encoded with utf-8 previously, which caused
problems with some characters.
minor changes
Merge pull request #82 from ForceField-IndieGames/Benedikt

Upgrade system, shield, adaptive street, new models, building rotation, bugfixes