status update

Finally posted a new tarball today. Lots of changes over the past few weeks:

1. 'datatype' syntax and 'normal' variants (though I've left in polymorphic variants as a 'stealth' feature)
2. more tests, and run_tests.py now verifies their output
3. 'let_reg' will store bindings into registers when certain conditions are met - this really cuts down on pointless allocation for local variables.

I feel like this is getting much closer to 'useful' status, and will hopefully begin work on a VM within the next couple of weeks.

Here's the tarball.