There was a subtle big in save_newobj(): it used self.save_global(t)

There was a subtle big in save_newobj(): it used self.save_global(t)
on the type instead of self.save(t).  This defeated the purpose of
NEWOBJ, because it didn't generate a BINGET opcode when t was already
memoized; but moreover, it would generate multiple BINPUT opcodes for
the same type!  pickletools.dis() doesn't like this.

How I found this?  I was playing with picklesize.py in the datetime
sandbox, and noticed that protocol 2 pickles for multiple objects were
in fact larger than protocol 1 pickles!  That was suspicious, so I
decided to disassemble one of the pickles.

This really needs a unit test, but I'm exhausted.  I'll be late for
work as it is. :-(