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

Ex 1: User selects constraints from the list => right click => select "select elements" from the contextual menu => The elements (edges,vertex) involved in the constraint(s) are selected.

Ex 2: User selects (a) constraint(s) => Clicks button in toolbar (if included by the user) => 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.
Sketcher new feature: Select Conflict and Redundant Constraints

Based (and solves) Mantis ticket:
http://www.freecadweb.org/tracker/view.php?id=1643

The ticket refers only to redundant, and ask for deletion.

Two commands are created, one for redundant constraints and other for conflicting constraints.

As usually removing one constraint of the "at least one" is sufficient, the implementation selects the constraints (but does not delete them).

The user therefore easily identify the constraints involved and decide to delete them.

This implementation takes into account the edit->Actsketch that ViewProvidedSketch creates for solving, as it is this instance the one that generates the messages in the Sketcher Taskbar.

No buttons in the toolbar by default (can be added by the user), but an hyperlink in the solver messages which triggers the selection of the appropriate command (conflicting or redundant).
Sketcher Redundant/Conflicting art by Jim
Sketcher visualization: Increase readability of redundant constraint solver message

Color changed to "OrangeRed" to improve readability.