Basic: step8 basics. Fix def!, let*, concat, scalars.

Basic: step8 basics. Fix def!, let*, concat, scalars.

- Move apply logic in swap! to APPLY function in types and use that
  for macroexpand
- Abort def! if error before updating the environment
- let* wasn't properly saving A2% for the final eval. Also, the
  environment release check should be against the top-level EVAL env,
  not the root repl env.
- (concat (list) ...) was broken so fix it to ignore empty lists that
  aren't in the trailing position.
- nil, false and true in the reader were always being returned as
  references (with an ref cnt) but we have the assumption that
  references (14) are not ref cnt'd and are always part of a compound
  type so fix the reader to just return the interned addresses.