migrate 7.x-2.3-rc1

Migrate 2.3 RC1
===============

Features and enhancements
- #1437076 - Make Migration class field mapping methods public.
- #1430528 - Document importance of migrating term parents first.
- #1418126 - Use node_delete_multiple on migrate-wipe.
- #1424632 - Improve user migration performance by reducing hash count.
- #1414616 - Automatically update migration arguments.
- #1364326 - Default --limit option to items.
- #1337640 - Properly optimize the SQL source query for highwater marks.
- #1366588 - Source plugin support has been refactored to put more of the common
processing in the base class. When implementing a source plugin,
implement performRewind() and getNextRow().
- #519906 - Added support for the core poll module (choices and votes).
- #1355940 - Track all source rows in the map table.
- #1358650 - Truncate text fields according to configured max_length.
- #941440 - Autodetection of source fields when unspecified.
- #1341776 - Add option to skip source counting.
- #1342936 - Pass source key in calls to Migration::createStub().
- #1335110 - Automatically lowercase MD5 passwords.
- #1331912 - Catch exception due to skipped beginProcess().
- #1337810 - Documented hooks in migrate.api.php.
- #1342322 - Added default implementation of prepareRow(), simplifying source plugins.
- #1336534 - Added MigrateSourceXML for efficient handling of large XML files.
- #1330552 - Provide more detail on bad field mappings.
- #1321078 - Display incomplete dependencies in the error message.
- #1321062 - Simple base class for field handlers.
- #1314448 - Added tnid to node destination handler.
- #1231492 - Added source handler for retrieving content from file directories.
- #1290706 - Centralize loading of XML.
- #1295040 - Support --update functionality in UI.
- #1304444 - Added static displayMessage(), deprecating showMessage().
- #1290706 - Centralize loading of XML.
- #1254398 - Prevent accidental emailing during migration.

Bug fixes
- #1447368 - Handle purely numeric PHP memory_limit.
- #1432802 - Default $options to prevent PHP 5.4 error.
- #1333656 - Remove content type/fields when uninstalling migrate_example_baseball.
- #1416012 - Cleanly handle NULL source key values in saveIDMapping().
- #1419086 - Better error handling in MigrateXMLReader::next().
- #1422114 - ID list array must be imploded for queries.
- #1372204 - Fix loss of pictures when updating users.
- #1364034 - Add cache_key option to sources, for disambiguation.
- #1354162 - Make sure messages are retrieved from the right connection.
- #1352648 - Update mode reapplied on each batch in UI.
- #1349246 - Postgres error updating migrate_log.
- #1342686 - Generalized needs-update support.
- #1341598 - filename/filemime not set in file_link/file_blob cases.
- #1342736 - drush options don't need -- prefix.
- #1340204 - MigrateDestinationFile::prepare() didn't call parent::prepare().
- #1336880 - Fix XPath handling in MigrateItemsXML::getIDSFromXML.
- #1334546 - Validate compound keys passed to handleSourceMigration().
- #1305338 - Corrected type-hint in MigrateSourceSQL constructor.
- #1305910 - MigrateDestinationTable now tracks inserted/updated records.
- #1284592 - Fixed error on empty term parents.
- #1300258 - Fixed error on unfulfilled term references.
- #1292462 - Group missing from drush options.
- #1290122 - Force destinations to implement __toString().
- #1290120 - Warnings updating users if roles not set.
- #1290118 - Warning in MigrateItemJSON::getItem()
- #1133096 - Failure to clear currentRow in MigrateSourceMultiItems.