More API re-works

Again, partially addresses #72. This time we move the MATLAB compatibility
functions to their own module and implement the 1d and 2d transforms using the
new-style API.

Some love has been given to naming as well with the old
``TransformDomainSignal`` class being renamed ``Pyramid`` and the attributes
also being re-named.

This results in quite a lot of API churn but it's best to get it over and done
with in one go.