Make python API more pythonic

[mmilata]

• get rid of getters and setters, use attributes
• provide __cmp__ method instead of cmp() (to allow operators for comparison)
• use __copy__ instead of dup()

[mmilata]

Implicit getters and setters: http://docs.python.org/2.7/c-api/typeobj.html?highlight=tp_getset#PyTypeObject.tp_getset

[ernestask]

Or just ditch these hand-rolled bindings altogether and start using GIR.