PlaneFit: Blender add-on, tiny improvement

The PlaneFit add-on wasn't very robust yet so I added a check for less than 3 selected vertices so a plane will only be fitted when it is sensible to do so. Gives a proper warning as well and the menu (In the 3d view, Add->Mesh in edit mode) now has a more readable label.

Availability

I have updated the add-on in my GitHub repository. (right-click on the link and select Save As .. to store the .py file somewhere where you can find it again )