Fixed draw order for extension area.
Setup protobuf framework. WIP.
WIP Added missing protobuf dependencies.
First usage logger prototype
Fixed encoding of blocks
Fixed computation of robot's movement.
Added logging for drop events. Some refactoring.
Added user events. Furhter refactoring.
timing
WIP
work on signal mapper
Logging of block events (button clicks, slider updates, note changes, ...)
Fixed compilation in case no protobuf lib is available/ no logging is desired.
Changed logging makro to USAGE_LOG to be more meaningful.
Added switch -usagelog to enable usage logging on startup.
Merge pull request #330 from SeverinKlingler/usage_logging

Usage logging prototype
Fixed compilation when protobuf is not found.
Main CMakeLists.txt does not look for protobuf any more.
Trying to work around issue #285 on Windows
Added option to save scene as png, jpg, bmp, tiff or ppm