objlist: Support list slice deletion.
py: Start making good use of mp_const_obj_t.
objboundmeth: If detailed reporting enabled, print object content.

Similar to closure and cell.
objstr: Make .[r]partition() work with bytes.
py: Don't try to "bind" types store as attributes of objects.

This was hit when trying to make urlparse.py from stdlib run. Took
quite some time to debug.

TODO: Reconsile bound method creation process better, maybe callable is
to generic type to bind at all?
objtuple: Go out of the way to support comparison of subclasses.

Two things are handled here: allow to compare native subtypes of tuple,
e.g. namedtuple (TODO: should compare type too, currently compared
duck-typedly by content). Secondly, allow user sunclasses of tuples
(and its subtypes) be compared either. "Magic" I did previously in
objtype.c covers only one argument (lhs is many), so we're in trouble
when lhs is native type - there's no other option besides handling
rhs in special manner. Fortunately, this patch outlines approach with
fast path for native types.