Wrap large Matlab value classes

[mducle]

Some Horace classes were designed as value classes - this includes all the re-written sqw, dnd, multifit and tobyfit classes which are extremely slow in Python because any changes to their properties which does not use explicit getter/setters needs to re-assign the class back, which involves copying a massive amount of data.

As such these classes should be wrapped in Python so they behave more like Python classes (e.g. what Matlab calls "handle" classes).