Improved logging and enum use in ASTInspector.
Reintroduce native Delegator extension to speed delegated calls.

This native implementation does method_missing all in Java code,
which provides the following benefits:

* No requirement for a frame or scope in method_missing logic,
  as with the pure-Ruby version.
* Direct lookup and dispatch to target method, rather than through
  __send__ logic.
* Only respond_to? check if method is not naturally defined, to
  catch respond_to_missing? and similar cases.
* Directly omit lines from backtrace rather than manually
  manipulating it (which did not always work due to our different
  formatting for backtraces that bubble all the way out).

This new version is nearly 2x faster than the pure-Ruby version.