changed model for anti backlash nut to render correctly for all sizes
small modifications to give the y axis spline the room it needs.
added stepper info and proposed choices for X/Y/Z axis
added a license and license files
added console output to list any real parts used so i can bom bom bom
license detail renamed/added
stepper motor models taken from Mendel90 repo
new fillet implementation, small changes to allow custom washer sizes,
flat nuts, bearing descriptions and console output of parts used
changed shape and design of z carriage. bearings now facing the back.

some code tidying and refactoring.
design and modelling of Z and Y axis largely complete

added motor mount parts and Z axis bar clamps.

modelled belts and pulleys for Y axis