1. Create abstract KinematicEngine, allow kinematic engine composition with + (thanks to Jan for suggesting that)
2. Move all KinematicEngine's to pkg/common/KinematicEngines.{hpp,cpp}
3. Change accels in GLViewer so that x,X,y,Y,z,Z make rhe respective axis point upwards etc
4. Change g/G to enable/disable grid (or selectively enable if pressed multiple times)
5. Remove button images in the qt4 ui, use unicode symbols instead
6. Make batch referesh once in 30s by default instead of 5s to avoid congestion on slow uplinks