variations of the type struct and its attachments. In Py3k, all type
structs have to have all fields -- no binary backwards compatibility.
Had to change the complex object to a new-style number!
This uses up to 12.5% overallocation, not entirely unlike list_resize().
Could probably use more tweaks for odd allocation patterns, TBD.
Also add __alloc__() method which returns the actually allocated size.
PS. I'm now convinced that we need something like "".join(); later.
Guido van Rossum