Add/fix some bytecode stack comments
Partial work for primitive Java interop (#73)

This gets some usage of int/boolean primitive Java interop working for
methods returning primitive values aren't working, but those same
methods do work when used from JavaIntegrationTest so I'm not sure
what's going on yet.

We also need to add support for all the other Java primitive data
types as well.
Fix returning integer values from overriden Java methods (#73)

This commit gets returning integer values created in JavaScript
working in overridden Java methods. A similar fix will probably need
to be made for float/doubles.
Fix returning the remaining numeric values from overridden Java methods (#73)

All numerics should be taken care of now, and this is where I'm
putting this on hold for a bit.
Merge pull request #74 from bbrowning/primitive-java-interop

Partial work for primitive Java interop (#73)