Add origin plane shortcuts to constraint tool

[jfellerLYK9Y]

Add the origin plane shortcuts (like in the mirror commands) to the constraint tool to make it easier to constrain parts to the origin instead of having to go to the tree.

Ground and Root works well if you want to create all 3 flush constraints, however with mirrored parts or parts that are used in multiple instances it does not work. Also for using the symmetry constraint.

This would be helpful to avoid having to scroll up and down the tree in large assemblies to pick between the origin planes of a part and the origin planes of the assembly when creating constraints.

[frank.gavilar]

This would be a great addition to the already improved constraining system!

Don't forget to add the origin axis as well though.

[thenottakenname]

Having the origin planes in the constraint window would cut down my work time significantly -- it takes forever in large assemblies to scroll up and down the part tree for every single part (angle constraint to origin plane in piping runs).

[andreas.ajax]

This is great!

I would like this to be showed visually as well. Let´s say you click "Pick part first" and then you can right click to select origin plane. This way you can work with the origin planes the same way you do with other faces.