Initial work
Sketcher new feature: Selects the elements associated with the selected constraint(s)

User selects (a) constraint(s) => Clicks button => The elements (edges,vertex) involved in the constraint(s) are selected.

Intended as visual aid to see which elements are being affected by a constraint.

Requested by Jim on thread:
http://forum.freecadweb.org/viewtopic.php?f=19&t=6875&start=10

Solving another Mantis ticket I can not find now.
Major bug fix: Extending the command to edit->ActSketch, not only SketchObject

The ViewProvidedSketch creates a temporary copy SketchObject for its solving.