Made BLI_delaunay_2d_cdt_calc better at tiny feature elimination.

The 'random' unit tests and some examples from the new boolean code
triggered asserts and crashes. This fixes those.
There is a new flag in the input that optionally disables a pass
over input to snap segment edges to other segments.

source/blender/python/mathutils/mathutils_geometry.c

@@ -1649,6 +1649,7 @@ static PyObject *M_Geometry_delaunay_2d_cdt(PyObject *UNUSED(self), PyObject *ar
   in.faces_start_table = in_faces_start_table;
   in.faces_len_table = in_faces_len_table;
   in.epsilon = epsilon;
+  in.skip_input_modify = false;
 
   res = BLI_delaunay_2d_cdt_calc(&in, output_type);