include source files up to three levels deep for the compilation
added starters/ folder including a first CommandData example and a registration function for all plugins in the starter/ folder called Register_Starters()
added REGISTER macro to starters.cpp, added group-objects.cpp to starters/commands/, updated file header of create-cube.cpp
updated copyright notice
added File Header section
added README for starters module
updated file headers of existing files. added commands/iter-hierarchy.cpp example and registered in starters.cpp
updated README. added commands/spheres-on-points.cpp example. changed register function name scheme.
updated file header copyright