Bugfixes (skybox+streets(#11))

The skybox turned black, when hovering over the gui.
The building costs for streets werde not correctly calculated. (Issue
#11)
Bugfix AnimationManager (#19 )

Two animations of the same value in opposing directions could previously
cause problems.
Graphical enhancements

Better building preview and nice new animations for tooltips.
Better building selector behavior (#23)

The building selector now moves out of the way while building. Also, the
camera can now be safely rotated without accidently leaving the build
mode.
Added textbox (#22)

Added a simple textbox with basic text editing. Only textinput and
character deleting is possible. No selecting and no cursor.
Added cityname and loading screen
Improved save files (#24)

Citys are now saved in binary files, rather than in plain text files.
It's gonna be a hard time for cheaters.
Enhanced textboxes (#25)

Textboxes now have a caret that can be positioned with the arrow keys.
Also, they support local copy&paste and the home and end keys work now.
Imroved loading panel (#8)

Up to 6 Cities are shown in the loading panel. Cities that are not
displayed can be loaded using the textbox.
Improved loading screen (#20)

Thumbnails are now displayed along with saved cities. Also the loading
panel now contains buttons for scrolling in the cities.
Graphical improvements for loading panel
Added automatic text wrapping to labels (#26)

Text in labels is automatically wrapped when the text is set. The label
tries not to rip apart word, when possible. But wehen the gap would be
bigger than 4 Characters, it does so anyway and sets a "-" on the line
end. Also, this commit contains some refactoring and also an enhancement
regarding textboxes (caret positioning via mouseclick!).
Localized strings (#28)
Merge pull request #31 from ForceField-IndieGames/Benedikt

Major GUI enhancements + bugfixes