Label Dispenser

This is for the Ultimaker challenge. FWIW, challenge wise, I'm a maintainer of MCAD and a meta-maintainer of github.com/SolidCode. I'm also THE RepRap/RepLab evangelist here in Finland ;)

Anyway, on to interesting stuff:
I've refactored the code, making the parametrization better, and added a roll holder so that a label roll can sit inside the dispenser. Currently the size of the roll is limited somewhat, I intend to refactor some more to make allowances for bigger rolls. Support for packing