EditCoinManager: Ensure rootpoint is higher than constraints

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Following new behaviour of highlighting root point on full constrained:
https://forum.freecadweb.org/viewtopic.php?p=555663#p555663

the rootpoint was lowered in virtual height with respect to the rest of points, so that
the color of any other overlapping point takes precedence.

However, this made it the same height as constraints, causing it to be unpickable in presence of
a colocated constraint:
https://forum.freecadweb.org/viewtopic.php?p=556114#p556114

Solution: Raise all points by one

src/Mod/Sketcher/Gui/EditModeCoinManagerParameters.h

@@ -72,11 +72,11 @@ struct DrawingParameters {
     const float zHighLines  = 0.007f; // Height used for on top rendered lines
     const float zHighLine   = 0.008f; // Height for highlighted lines (selected/preselected)
     const float zConstr     = 0.009f; // Height for rendering constraints
-    const float zRootPoint  = 0.009f; // Height used for bottom rendered points
-    const float zLowPoints  = 0.010f; // Height used for bottom rendered points
-    const float zHighPoints = 0.011f; // Height used for in-the-middle rendered points
-    const float zHighlight  = 0.012f; // Height for highlighted points (selected/preselected)
-    const float zText       = 0.012f; // Height for rendered text
+    const float zRootPoint  = 0.010f; // Height used for bottom rendered points
+    const float zLowPoints  = 0.011f; // Height used for bottom rendered points
+    const float zHighPoints = 0.012f; // Height used for in-the-middle rendered points
+    const float zHighlight  = 0.013f; // Height for highlighted points (selected/preselected)
+    const float zText       = 0.013f; // Height for rendered text
     //@}
 
     /// Different categories of geometries that can be selected by the user to be rendered on top, in the middle or in the bottom