Path: More ambitious step-over and break optimizations

Extend the work from #3496 to allow the safe optimization of more
complex step transitions.

- Use the actual safePDC path for short step transitions and breaks,
  currently up to 2 cutter diameters. This value is chosen to cover
  basically all typical end step-overs, including those with heavy skew.
  Extending this much further (up to the break even point for a retract &
  rapid) will need some careful thinking for multi pass paths.
- Coordinate offset tolerances with per-operation tessellation
  tolerances, to avoid tessellation artifacts messing up paths by
  causing false retracts.  Such retracts can cause entire steps near
  vertical areas to be falsely skipped, which would cause a major
  deviation from the target model.  By considering per-job tolerances, we
  allow users to safely save computational resources by computing roughing
  operations with lower precision, or selectively increase precision for
  finish passes.
- Refine the default tessellation tolerance to GeometryTolerance / 4.
  This makes sure that the job GeometryTolerance is respected by
  operation defaults.

src/Mod/Path/PathScripts/PathSurfaceSupport.py

@@ -114,9 +114,9 @@ class PathGeometryGenerator:
                     fCnt += 1
                     zeroCOM = zeroCOM.add(FreeCAD.Vector(comF.x, comF.y, 0.0).multiply(areaF))
                 if fCnt == 0:
-                    msg = translate('PathSurfaceSupport', 
+                    msg = translate('PathSurfaceSupport',
                         'Cannot calculate the Center Of Mass.')
-                    msg += ' ' + translate('PathSurfaceSupport', 
+                    msg += ' ' + translate('PathSurfaceSupport',
                         'Using Center of Boundbox instead.') + '\n'
                     FreeCAD.Console.PrintError(msg)
                     bbC = self.shape.BoundBox.Center
@@ -910,22 +910,26 @@ class ProcessSelectedFaces:
         '''_calculateOffsetValue(self.obj, isHole, isVoid) ... internal function.
         Calculate the offset for the Path.Area() function.'''
         self.JOB = PathUtils.findParentJob(self.obj)
-        tolrnc = self.JOB.GeometryTolerance.Value
+        # We need to offset by at least our linear tessellation deflection
+        # (default GeometryTolerance / 4) to avoid false retracts at the
+        # boundaries.
+        tolrnc = max(self.JOB.GeometryTolerance.Value / 10.0,
+                     self.obj.LinearDeflection.Value)
 
         if isVoid is False:
             if isHole is True:
                 offset = -1 * self.obj.InternalFeaturesAdjustment.Value
-                offset += self.radius + (tolrnc / 10.0)
+                offset += self.radius + tolrnc
             else:
                 offset = -1 * self.obj.BoundaryAdjustment.Value
                 if self.obj.BoundaryEnforcement is True:
-                    offset += self.radius + (tolrnc / 10.0)
+                    offset += self.radius + tolrnc
                 else:
-                    offset -= self.radius + (tolrnc / 10.0)
+                    offset -= self.radius + tolrnc
                 offset = 0.0 - offset
         else:
             offset = -1 * self.obj.BoundaryAdjustment.Value
-            offset += self.radius + (tolrnc / 10.0)
+            offset += self.radius + tolrnc
 
         return offset