E3D Toolchanger tool lock verification switch

Add a switch to verify that there is a tool loaded in your E3D toolchanger. also know if the bayonet has released your tool when you unlock the C axis. This will stop the toolchanger from dropping a tool when you restart the printer and forget that there is a loaded tool. it will also stop the printer if it tries to pick up a tool and it fails to properly lock the tool. some have suggested that it would be a good idea to have automatically turn off the heaters. the attached code does not do that.

included are .g system file examples, Autodesk Inventor part files, Fusion 360 part files, a reprap macro to help release the tool after a failure, 3D printer files (stl)

The switch you need to get is the Z endstop switch from E3D:
https://e3d-online.com/products/toolchanger-z-endstop

This is a crappy video showing the parts:
https://youtu.be/7ZOS8Bsa4OM

cheers
dave