Bowden extruder inductance sensor mount

I needed an inductance sensor mount for the Tech2c version 2 E3D V6 Bowden mount for Prusa i3. (See http://www.thingiverse.com/thing:1632847)

This part replaces the 'Bowden_clamp_v2.stl' file. I use the 12mm diameter sensor (LJ12A3-4-Z/BX).

The photo is with my spare extruder, but I actually use it on my printer with my genuine E3D V6.

The sensor offset from the nozzle is 30mm in the X direction and 8.5mm in the Y direction (for both hole sizes). For Marlin and my printer I have the following values in Configuration.h:

`#define X_PROBE_OFFSET_FROM_EXTRUDER +30`
`#define Y_PROBE_OFFSET_FROM_EXTRUDER +8`
`#define Z_PROBE_OFFSET_FROM_EXTRUDER 0`

I have added a second STL file with an 18mm hole.

25/Jun I have added a fan duct for a 40mm fan while waiting for my blower fan.

8/Jul I have added more STL files with 4mm holes for the clamp to extruder body. The first number is the sensor hole size and second screw hole size.

I have added a 12mm sensor hole size withou