Make the RenderData const, where required to change it for the blend masks use a copy.
SpaceStation.cpp - don't render the city OR the station if we're too far away.
ModelBody.cpp - reserve the vector for the number of lights.
CityOnPlanet.h/cpp - Remove the per building enabled flag, instead keep a list of the enabled buildings and only draw those. Also add a city wide m_clipRadius flag and test the whole city before trying to render buildings.
Reduce the amount of work the CityOnPlanet::Render method is doing per building.
Merge branch 'master' of https://github.com/pioneerspacesim/pioneer into ProfileCities

Conflicts:
	src/scenegraph/Billboard.h
	src/scenegraph/Group.h
	src/scenegraph/LOD.h
	src/scenegraph/ModelNode.h
	src/scenegraph/Thruster.h
Compiling again.
Merge branch 'master' of https://github.com/pioneerspacesim/pioneer into ProfileCities
Merge branch 'master' of https://github.com/pioneerspacesim/pioneer into ProfileCities
Tidyup vcxproj by removing some defunct files.
Limit distance at which cities are rendered.
Delete defunct and commented line.
Make sure that I'm actually using the centre of the city rather than the spaceport location.
Merge remote-tracking branch 'fluffyfreak/ProfileCities'