New table_copy destination plugin. Useful when you just have to make a straight copy of one table from legacy to drupal and you would rather use migration framework instead of export/import. Migration also has handy highwater feature.

Allow individual migrations to have prepare methods. These are called last by MigrateDestinationEntity::prepare. Illustrate this feature in the BeerUser migration by converting a Denver ISO time to unix timestamp.

#737174 by moshe weitzman. Set needs_update=1 in mapping table when a referenced entity has not yet been created. useful for articles with 'related articles' Field, for example.

Modernize filefield handler so it has an arguments method ... Also comment out pid in BeerComment migration since it is throwing an error which I can't debug right now.