E3D Titan Brackets

Updates to the [E3D Titan Bracket](https://www.thingiverse.com/thing:1477900) design kindly provided by [Joshua Rowley](https://www.thingiverse.com/joshuarowley42/about) of [E3D](https://e3d-online.com/)

These updates were primarily made so the bracket could mount on v-slot at varying angles, and would work with existing 10mm bolts and t-nuts.

There are two versions. v2 is the original remix, v3 is some further alterations made.

Changes:
- Holes are now slots to allow screws to be in varying positions
- Base is now 5mm thick so 10mm screws will work without extra spacers
- mount is reduced in length - the new slots should make up for the loss of the extra screw holes

v2 changes:
- mounting plate for motor is 0.2mm thinner to give more bite to screws to motor

v3 changes:
- added 8mm standover height. I found when mounting the Titan on 20mm v-slot either the extruder wheel, or thumb screw would overhang. This gets in the way of wheels running on the side of the v-slot