most of the work lately is going on in the leo-ctx5 branch of parrot.
- everything's converted to the new calling conventions.
- taking advantage of the new CC, we eliminate a lot of boxing and unboxing of values between simple registers and PMCs.
- eliminate "two value return" : before, if we called [error foo], it would return a tuple of (TCL_ERROR, "foo"). After this patch, it throws an exception. This was historically done because of the state of exceptions, but that hasn't been an issue for some time. Not only should this be faster in the non-error case, it's cleaner
We're now passing 100% of the tests (thanks to leo for a recent GC fix.)
