Prusa i3 Bowden E3Dv6 Integrated Inductive Sensor Mount

Remix of aaroncm's excellent E3Dv6 mount for Prusa i3.

I've made some changes to make it more to my liking:
* The inductive sensor is integrated in the mount for smaller form factor and higher stability.
* Distances between parts are smaller. This makes the distance between the sensor and the nozzle smaller, and should give you a bigger print surface when using two hot ends.
* More screw holes added for the hot end mount for added stability.

I also removed the sink for the screws attaching the mount to the X carriage, to make it easy to use washers on those screws. You'll need longer screws, probably M2x30.

I have included both a single hot end version as well as a dual hot end version, as well as all sketchup files. I haven't tried the dual hot end version since I only have one.
Also included is a sketchup file with all the separate parts so you can mix and match.