The core functionality is to calculate and store tp_mro and tp_bases
instead of just tp_base.  This gives the runtime a bit harder of a
time to bootstrap itself since now a fully-built class depends on
a few more classes, so the bootstrapping section got larger:
- object_cls (base of the tp_base hierarchy)
- type_cls (base of the metaclass hierarchy)
- str_cls (for ht_name)
- tuple_cls (for tp_mro)
- list_cls (for calculating the mro)

There were a few places that needed to be updated now that we have
multiple inheritance:
- typeLookup()
- isSubclass()
- typeNew()
- super()

This change doesn't even attempt to add multiple inheritance rules
around old-style classes.