Last bits of PDD 15 implementation

[Allison Randal]

I'm about half-way through a quick classification of the failing PDD 15 
tests (in t/pdd15oo). A number of the failures are quick things anyone 
could pick off, so I'll share the list:

<http://rakudo.org/parrot/index.cgi?pdd_15_remaining_features>
We're only failing 157 out of 764 tests, so we're getting quite close 
being able to use the new object implementation as a drop-in replacement 
for the old object implementation.

Allison