Sketcher: UI Improvement Smart button for constraints and geometry toogle/creation

==================================================================================

Geometry button:
- if no object selected, the legacy toggle icon has a new functionality, switch to/from creating in construction mode
- if object selected, it has the legacy functionality
- the button can be clicked during "continuos creation mode" to switch from creating to/from creating in construction mode

Constraint button:
- The button is not selectable if nothing is selected (it would be impossible to determine the effect)
- When constraints are selected, the button toggles the constraints to/from Driving.
- When geometry is selected, the button switches from/to reference mode, the change is apparent from the color of the constraint icons.

Continuous creation mode:
- Default changed so that it is active unless you change it in settings

Updated terminology

src/Mod/Sketcher/Gui/Workbench.cpp

@@ -177,7 +177,6 @@ inline void SketcherAddWorkbenchGeometries(T& geom){
             << "Sketcher_Trimming"
             << "Sketcher_External"
             << "Sketcher_ToggleConstruction"
-            << "Sketcher_GeometryCreationMode"
             /*<< "Sketcher_CreateText"*/
             /*<< "Sketcher_CreateDraftLine"*/;
 }
@@ -206,8 +205,7 @@ inline void SketcherAddWorkbenchConstraints<Gui::MenuItem>(Gui::MenuItem& cons){
             << "Sketcher_ConstrainSnellsLaw"
             << "Sketcher_ConstrainInternalAlignment"
             << "Separator"
-            << "Sketcher_ToggleDrivingConstraint"
-            << "Sketcher_ConstraintCreationMode";
+            << "Sketcher_ToggleDrivingConstraint";
 }
 
 template <>
@@ -230,8 +228,7 @@ inline void SketcherAddWorkbenchConstraints<Gui::ToolBarItem>(Gui::ToolBarItem&
             << "Sketcher_ConstrainAngle"
             << "Sketcher_ConstrainSnellsLaw"
             << "Separator"
-            << "Sketcher_ToggleDrivingConstraint"            
-            << "Sketcher_ConstraintCreationMode";            
+            << "Sketcher_ToggleDrivingConstraint";            
 }
 
 template <typename T>