Overloaded ops, compiler working.

Ok, the compiled part is also in place, working, and committed.
Now we have (verified, compiled and interpreted):

=09+ -
=09+=3D -=3D
=09=3D < > !=3D =3D=3D
=09++ --

There are four (at the present simple) tests:

overload_pluseq.moto
overload_math.moto
overload_rel.moto
overload_incdec.moto

that are based on IntSet and Enumeration (the latter for the ++, even if=20
probably arbitrarily choosen...).

Now the biggest challenge: arrrrghays["groan"]!

=09Stefano