Revert "Increased resilience of minimal_bounding_sphere method"

This reverts commit 40f500c, moving all miniball-related changes to #178.

Author: janbridley

coxeter/shapes/polyhedron.py

@@ -556,31 +556,21 @@ def minimal_bounding_sphere(self):
                 'directly from PyPI using "pip install miniball".'
             )
 
-        # Define a check function to ensure points lie within a sphere
-        def points_within_sphere(points, center, radius):
-            return np.linalg.norm(points - center, axis=1) <= radius
-
         # The algorithm in miniball involves solving a linear system and
         # can therefore occasionally be somewhat unstable. Applying a
-        # random rotation will usually fix the issue, and checking if
-        # points lie inside will guarantee a correct answer.
-        max_attempts = 20
+        # random rotation will usually fix the issue.
+        max_attempts = 10
         attempt = 0
         current_rotation = [1, 0, 0, 0]
         vertices = self.vertices
         while attempt < max_attempts:
             attempt += 1
             try:
                 center, r2 = miniball.get_bounding_ball(vertices)
-                assert np.all(points_within_sphere(vertices, center, np.sqrt(r2)))
                 break
             except np.linalg.LinAlgError:
                 current_rotation = rowan.random.rand(1)
                 vertices = rowan.rotate(current_rotation, vertices)
-            except AssertionError:
-                print("Miniball sphere does not contain vertices. Retesting...")
-                current_rotation = rowan.random.rand(1)
-                vertices = rowan.rotate(current_rotation, vertices)
         else:
             raise RuntimeError("Unable to solve for a bounding sphere.")