Issue #2333029 by twistor, MegaChriz: Extend mapping API to allow for defaults and multiple callbacks

Issue #2379915 by hydrant-mark, twistor: Taxonomy Mapper: Assumes there will only ever be one matching term

Issue #1884516 by aaronbauman: Import with taxonomy term mapping fails if term name exceeds db size.

Issue #1884516 by aaronbauman: Import with taxonomy term mapping fails if term name exceeds db size.

Issue #1033202 by jamesdixon, jamsilver, twistor, james.williams, Steven Jones, vordude, j0rd, mErilainen, gmario, rickmanelius, imclean, dasjo, guillaumev, jlyon, gilgabar, elliotttf, mukesh.agarwal17, patcon, wesnick, Bevan, kreynen, Grayside, fago, spotzero: [Meta] Generic entity processor.

Issue #1019688 by johnv, philipz, twistor, sin, ts145nera, David Hernández: Fixed Taxonomy mapper options: term name +tid, term name, tid, guid (avoids mapping error for Numeric taxonomy term, too).

| dasjo: Fixed taxonomy_node_get_terms() doesn't work with drupal 7.

- DRUPAL-7--1-0-alpha2 http://github.com/lxbarth/feeds/tree/DRUPAL-7--1-0-alpha2
and
- DRUPAL-7--2-0-alpha1 http://github.com/lxbarth/feeds/tree/DRUPAL-7--2-0-alpha1

#908582 XiaN Vizjereij, alex_b: Fix 'Cannot use object of type stdClass as array' error in mappers/taxonomy.inc.

  language, user properties from parent feed node. Note: Signatures of
  FeedsProcessor::map(), existingItemId(), FeedsParser::getSourceElement()
  changed.