Add methods to remove spline edges from shapes

Namely, anything created from Disks that now contain spline edges;
these do not get updated during optimization and that will produce bad
cells.

Also, update optimization examples that are affected by that.

examples/complex/cyclone/regions/inlet.py

@@ -40,9 +40,8 @@ def create_inlet(self):
         )
 
         for op in inlet.operations:
-            # TODO: remove edges from face/operation
-            op.top_face.edges = [Line(), Line(), Line(), Line()]
-            op.bottom_face.edges = [Line(), Line(), Line(), Line()]
+            op.top_face.remove_edges()
+            op.bottom_face.remove_edges()
 
             for point in op.top_face.points:
                 # move points on inlet's end face so that they touch cyclone body,

examples/optimization/diffuser_free.py

@@ -26,6 +26,14 @@
 
 mesh.set_default_patch("walls", "wall")
 
+# Internal edges in Cylinders are Splines by default;
+# In this case their endpoints will be moved ('optimized') but not
+# the points in between; this will create bad cells. Either re-define these edges after optimization
+# or remove them altogether.
+diffuser.remove_inner_edges()
+small_pipe.remove_inner_edges()
+big_pipe.remove_inner_edges()
+
 # Assemble the mesh before making changes
 mesh.assemble()
 

examples/optimization/diffuser_line.py

@@ -10,6 +10,7 @@
 # The setup is the same as the diffuser_free example
 # except that here vertices are only allowed to move
 # axially in a straight line.
+# See diffuser_free for comments.
 
 small_pipe = cb.Cylinder([0, 0, 0], [2, 0, 0], [0, 1, 0])
 small_pipe.chop_axial(start_size=size)
@@ -23,19 +24,22 @@
 
 big_pipe = cb.Cylinder.chain(diffuser, 5)
 big_pipe.chop_axial(start_size=size)
+
 mesh.add(big_pipe)
 
 mesh.set_default_patch("walls", "wall")
 
-# Assemble the mesh before making changes
+diffuser.remove_inner_edges()
+small_pipe.remove_inner_edges()
+big_pipe.remove_inner_edges()
+
 mesh.assemble()
 
-# Find inside vertices
 finder = cb.RoundSolidFinder(mesh, diffuser)
 inner_vertices = finder.find_core(True)
 inner_vertices.update(finder.find_core(False))
 
-# Release those vertices so that optimization can find a better position for them
+
 optimizer = cb.Optimizer(mesh)
 
 for vertex in inner_vertices:

src/classy_blocks/construct/shapes/round.py

@@ -71,6 +71,13 @@ def set_outer_patch(self, name: str) -> None:
         for operation in self.shell:
             operation.set_patch(self.outer_patch, name)
 
+    def remove_inner_edges(self) -> None:
+        """Removes spline edges from cylinders.
+        This needs to be done in cases where any of the start/end plane points will move
+        (due to optimization or manual adjustments)."""
+        for face in (*self.sketch_1.core, *self.sketch_2.core):
+            face.remove_edges()
+
 
 class RoundHollowShape(RoundSolidShape):
     def __init__(