fix camera orientation setting in navigation. #40

back- and forthcalculating from eye+center+up to rotation center+rotationQuaternion now works properly
add left/right center rotation with Q/E. #40
fix movement direction when rotated. #40
normalize movement speed, add speed scale, add speed boost when holding SHIFT. #40
add mousewheel zoom/pitch to navigation. #40

* Navigation now receives GLFWScrollEvents.
* pitch with mouse wheel
* zoom with mouse wheel while holding SHIFT
clean up unnessecary include. #40
update readme. #40
Merge remote-tracking branch 'origin/nirvana_40' into nirvana_terrain_40
different rendering for base and water tile #41