This reverts commit adb717b5, reversing
changes made to aabf84cd.

Incoming

Classes with no fields don't really make sense, so forbid them
(just as records with no fields aren't allowed). Closes #2509

There were bugs in the code path for initialization of non-spilled
locals, the code-path is hit approximately never, and mem2reg can do
it for us.
I think this will let us kill spill_map.

This was a result of changing the vector representation to contain
a box header.

This reverts commit 422aec85.

Heavily rework lint infrastructure. Split it into two passes: one that builds the table and one that does the checks. Build the table early and make session know about it fo reasy use.

trans now can safely assert that it never sees a type param

Moved log method into logger class better than scheduler