Fix serialize op return type.
Port a few of the basic serialization primitives.
Port more of the lower-level serializations.
Get serialization loop and assembly mostly ported.

With this, it's probably not so far from producing output; misses base
64 and any object knowing how to serialize itself.
Add base-64 encoding of serialized output.
Get endianness right.
Fix thinko.

Can now round-trip an empty SC.
Be more eager about owning STables.
API consistency.
Serialization of (non-inlined) P6int/P6num/P6str.
Get inlined P6int/P6num/P6str to serialize.
Serialization of P6opaque instances.
Eliminate a warning.
Ensure boot types go in the core SC.
VMArray serialization.
Get hash serialization in place.
Final bits to pass all serialization/01-basic.t.
Run t/serialization/01-basic.t in selftest.

Should pass entirely; good to get some more testing of it.
Implement STable serialization.
Set type check cache properly for KnowHOWs.