* Fix all hash checks that checked Bucket.arKey for NULL, when it was changed

* Fix all hash checks that checked Bucket.arKey for NULL, when it was changed
  to char[1], these checks should have been changed to Bucket.nKeyLength==0
* Support runtime declaration of functions.  I ended up changing the grammar
  to catch top level functions vs. nested functions.  The reason is simple -
  if we don't have functions properly declared at compile-time, function calls
  cannot be resolved at compile time, and have to be resolved at runtime, which
  ends up being much much slower (without the optimizer, that is).
  It's no biggy though, the grammar change isn't that bad.