A bit of renaming and moving code around in is mesh.
Added getter for getting the tetrahedra of a face.
Created difference and union operations on key sets (should be moved to class and replace simplex set).
Created a new version of the flip_23 function. It is not tested or used yet.
Added a getter for getting the faces of an edge.
Added a getter for getting the tetrahedra of an edge.
A bit of renaming.
Added a new flip_32 function. Not used or tested yet.
More getters for simplices and update.
Added a simplex set union.
Added is_neighbour functions.
Added new flip_22 and flip_44 functions. Not used or tested yet.
Added getter for getting edges of a node.
Made the validity check much more thorough.
Added is_neighbour function.
Bug fixes in the new flip and collapse functions.
Added a create_tetrahedra function which creates a set of tetrahedra given a set of interior and exterior faces.
Added a create faces function which creates a set of faces from an interior edge and a set of exterior edges.
Bugfixes in create tetrahedra function.
Using the create_tetrahedra and create_faces functions in flip23 and flip32.