Add cwd to the load path in Makefile.
Remove implemented features from MISSING.
Add implicit (begin ...) for while loops.
Convert test suite to use srfi-64.

Along the way, I discovered a bug in the test suite: iol-eq-tests was
comparing the actual result against itself, not the expected result.
Fortunately, the tests still pass after fixing this.
Move some whitespace around.
Add empty to Makefile & .gitignore.
Start documenting the accepted syntax.

Also, delete the MISSING file; we'll document desired but unimplemented
features as we go.