logitech MX Ergo dongle and cleaning stick storage

based on the dongle storage piece by dlofstrom, this adds a stick to remove the trackball for cleaning, storage for the stick, and places to mount magnets so it's less messy when taking it apart.

ErgoMXDongleStorage.stl is the original piece, only needed if you want to use the openscad file.

otherwise, just print mx_ergo_wedge.stl and mx_ergo_stick.stl (I did this one solid).