Implement ice levels (flexible for more terrain types)

This is done by implementing an additional mode variable.
Changes incorporated:

 * Different level initializers
 * Different color material (defaults)
 * Different coefficients of friction

Additionally, level initializers extracted to LevelDeclarations.h.

This closes #18.
Merge branch 'master' of github.com:WChargin/car2014

Conflicts:
	AndroidProjects/Drive2/jni/STRO_NEW.h