* Agent now respects attribute type restrictions on trace/segment attributes, as
  well as error event/trace attributes.

* Fixes potential for  error on
  Transaction/Trace end.

* Custom events no longer accept attributes with invalid types.

  The only attribute types accepted by the backend are , , and
  ; any attribute assigned to a custom event outside these types would be
  dropped on ingest. The agent now filters these attributes out, and logs out a
  helpful message detailing the issue.