- Cleanup whether types passed to functions are evaluated or not.
At this point, I think types should always be evaluated. That means
passing a quote character in front of non-keyword types. So
:char and '(:array :char) is the way types should be specified.
This may involve stripping the (quote ...) for some implementations
like CMUCL which doesn't evaluate the type argument.

- Cleanup the meaning of (def-array). Add size parameter

- Change dereferencing of pointers to :char and :unsigned-char types.
May need to have ensure-char as routine to correctly handle setf
expansions. CMUCL strtol is broken because of signedness.  Right now,
LW prefers unsigned and CMUCL prefers signed string arrays. I lean
to having unsigned be the default type.

- Add def-union routine

- Split implementation-dependent code into separate files in preparation
for MCL and CormanLisp ports.