Added cutout to access ICSP contacts

Added a cutout to the insulator so that the ICSP contacts for
reprogramming the mcu can be accessed in-situ.
Added capsense variant of the insulator

Added a variant of the sensor board insulator to suit the prototype
(hacked) capacitive height sensing board
Add X-carriage design

Added .scad and .stl files for Ormerod X-carriage