Embedded sliding front door for CraftBot

This space saving sliding front door is designed to nicely fit CraftBot's internal free space on the sides and bottom of the build plate. It is seen from outside only three transparent polystrerol plates and a thin handle to open/close. Design is assembled directly to CraftBot's original screws on the sides. Whole build volume is still accessible when the door is all the way down. When build plate is completely down, door can still be used without any problem.

Transparent plates are 365 x 88 mm2 with 2.3mm thickness. I did fine tune the dimensions of the plates and sliding links which hold them.

As a second option, you can have 4x 365 x 66 mm2 plates in the same rails. New Door_links_small_left_10.stl file contains new links for 66mm tall plates.

Refreshed *_10.stl files:
- tested with CW 1.08 beta #10237 (PC) and CW 1.06 beta #4248 (Mac)

Improvements with *_10.stl
- Door_rail_horizontal_left_10.stl file is updated, corner is lowered another 2mm so that last p