Use PackfileView instead of Eval PMC

Eval PMC is deprecated in Parrot and will be removed when the eval_pmc branch merges. This patch makes a few changes:

1) Uses the .compile() method of the IMCCompiler PMC, instead of a simple invoke (which is also deprecated)
2) The return value from .compile() is a PackfileView, not an Eval. Update all uses of this return value to use the PackfileView interfaces

The changes work with Parrot master right now and so can be applied prior to the eval_pmc branch merge for testing.