While not as pretty this should work much better mechanically
based on the results from the last test print.
* Added room for the plugs to slide from the middle outwards
* Made back reinforcement much larger so it connects the piece that is
split by that plug channel
* Removed separate board cutout (not needed anymore)
* Fix cable channel (was cutting through end caps)
* Change shelling parameters so it keeps a cap on both ends
* Adjusted segment breaks for new reality
* TODO: adjust rear hinge design to be flat and not "envolving"
