Remove unnecessary class typechecking code

Also add a test for this part of TR. In particular, it
handles registering syntax definitions that are found in
a class body.
Re-enable and fix a TR class test

It turns out the test was wrong instead of the implementation.
In particular, it reversed the internal/external name and thus
the error it failed with was correct (though not the intention of
the test).
Basic optimizations for extflonums.
Add missing forms to TR docs.
More extflonum optimizations.
Tests for extflonum optimizations.
Export the ExtFlVector type.
Add extflvector optimizations.
Fix extflonum tests for line numbers.
Typo.
Be more conservative when reporing potentially exact arithmetic.
Optimize expt on floats.
Add -l flag to `raco test`.

Behaves similarly to `-l` for plain `racket`.
Up timeout for `tests/racket/link`.
Add remaining racket/list functions to TR base-env
Fix inference for dotted and starred arr types.
get-filename might return #f; check for that properly
adjust language test for new letrec semantics
Add pointer to the `syntax/modresolve` docs.
Add missing forms to TR docs.