CNC 1610 upgrades/remixes

A collection of assorted upgrades for my Linksprite 1610 CNC.

1. remix of [Despair's Z plate](https://www.thingiverse.com/thing:2766350) to add a tab to tie the endstop wires to; wires connecting to moving parts like to break without strain relief.

2. remix of [Despair's X mounts](https://www.thingiverse.com/thing:2766350) to put the X endstops on the bottom. This keeps the top end of the CNC clean and I don't have to worry about any Z wires catching on anything. There's a loss of X travel