Issue #1039466 Add some warning messages if the widget or formatter is missing when the field is migrated, but allow the migration, they will be set to use the default widget and formatter.

Issue #1039466 We need to switch the file module for file and image fields even if they use a custom widget or they will not show up as fields that can be migrated. Best we can do is display anything that has a 'imagefield' or 'filefield' prefix.

Issue #1039466 Make sure number migration code does not break when migrating a field that has a custom number formatter.

Issue #1150790 Make sure empty values are not saved in migration to match bahavior when new empty values are submitted.

Switch the field definition batch to process one field at a time to avoid timeouts on sites with lots of fields.

Issue #1093844 by dww, Fix PHP warnings from content_migrate.filefield.inc on undefined legacy settings.

Did some clean up of the List test and reverted the code that tried to check the module name for formatters, because it doesn't work.

#1044140, #1044032, #1056174 by KarenS and bfroehle, lots of fixes to tests to avoid exception errors and make it more flexible.

#781088 Reorganize Content Migrate files for efficiency, and also to make it easier to use the individual module code as examples on how to implement the hooks.

#781088 by Island Usurper, loganfsmyth, and mattbatt, fixes to get imagefield and filefield data migrated.

Rewrote content_migrate to migrate one data record at a time, with a drupal_alter() before inserting it into the new table, to allow fields like imagefields to re-organize the data in the new table.

Add more information to the drupal_alter -- field info when altering an instance and instance info when altering a field -- for settings that are being moved from field to instance or vice versa. Initial attempt to handle the imagefield migration.

Add installation function to content migrate that will swap the stored content_extra_weight values to the new field_bundle_settings variable. Also properly set the body weight, which is otherwise not right.

#781088 More work on content migrate. Fix allowed values to make them into arrays, to match the new way that lists are stored.

node_reference and user_reference field types now live in the 'references' project - http://drupal.org/project/references

Kudos @swentel and @stalski for moving the code forward and taking over maintainance