Add config file formats for Box

[lmh91]

Add some ways to define a box primitive:

box:
   widths: [2,2,2] # or 

   # halfwidths: [1, 1, 1] # or

   # hX: 1
   # hY: 1
   # hZ: 1 # or 

   # x: 1 
   # y: 
   #   from: -1
   #   to: 1
   # z: 1

  origin: [0, 0, 0] # optional
  rotate: 
    Z: 0 # optional

Origin can also be specified like

origin: 
  x: 0
  y: 0
  z: 0 # or

origin: 
  x: 1 # -> origin at (1, 0, 0)

Also add functions get_origin and get_rotation which read in the optional fields origin and rotate.
These will also be used in the read-in of the other primitives (next PR's).

The rotation is applied before the translation to the origin.

[fhagemann]

Thanks for using commit messages that well describe what you are doing ;)