Remove Identifier
Change ccc.core.build semantics yet again
ccc.core.build can map lists now too.
Correct improper list mapping
Remove Syntax primitives.

Yeah. I've become convinced that hygienic
syntax transformers are too expensive to
get right and that low-level transformers
will be fine for this language.

So first step: Remove Syntax objects.

This breaks everything. Fixes incoming.
Remove remaining remnants of hygienic macro support
Restore balance.

All tests pass again. Basic syntax forms are functional again,
expansion, compilation, and evaluation are all separate phases,
and each is implemented in CPS with thunks. Phew.