Adds the SolarPatchGeometry
Merge branch 'master' of github.ugent.be:SKIRT/SKIRT

Conflicts:
	SKIRTcore/SKIRTcore.pro
Minor change in SolarPatchGeometry
adjust SolarPatchGeometry boiler plate to avoid warnings in modern compilers
Adds the SpiralStructureGeometry decorator class
adjusted so the code now doesnt use curly brackets to read in the bulge
and stellar component.
adjusted so a qlist of frames is used to allow multiple components
Adjusted FitSKIRT so it can handle a list of stellar components. ONLY
the case for the two components has been implemented at this point.
Adjusted some remaining bulge-to-disk specific implementation
Adjusted the luminosity boundary conditions so it does not assume a 2D
simplex for optimization
Added 1D luminosity fitting support using a GoldenSection optimization
method.
Added the ability to fit 3 or more stellar components using genetic
algorithms. This has not been extensively tested yet at this point.
fix writeStellarComps feature for 3 or more stellar components
remove ExpDiskSpiralArmsGeometry; use SpiralStructureGeometry decorator instead
fix density profile of SolarPatchGeometry