Merge pull request #1 from scgilardi/master

some tweaks to conditionals
Only emit "ok" on newline.
Add else.
Add do/loop. Untested.
Add begin/again.
Add !c and @c for fetch/store of single bytes.
Fix begin/again looping.
Test for begin/end and do/loop.
A bunch more stack primitives.
Make cell into union to get rid of all these warnings; thanks Steve!