fix GenericType operators

[erickvermot]

In current implementation, GenericType does not inherit from any other class, and for that reason has to implement its own operators methods, like __add__ etc...
The problem is that this leads to possible mistakes (like in the current definition of __lt__ - see bellow), and also forbid GenericType s from being used with operators that are not included in the definition (like with __int__, or __mod__).
A much simpler solution is to make it inherit from python primitive types, as proposed here: #198 (comment) .

current problems:

>>> a = GenericType(2)
>>> a > a
True

>>> int(a)
TypeError: int() argument must be a string, a bytes-like object or a number, not 'GenericType'

>>> a // 2
TypeError: unsupported operand type(s) for //: 'GenericType' and 'int'

[cemsbr]

The first is fixed:

>>> from pyof.foundation.base import GenericType
>>> a = GenericType(2)
>>> a > a
False

int(a) and a // 2 don't make sense for children like DPID, for example.