image 5.x-2.0-alpha5

Bug fixes since last release:

- #207557: update 5-1 to 5-2 gives user warning: Duplicate entry '611-thumbnail' for key 1 query in image_update_5200 by joachim: (Revisited) Fixed out of sync image_update_5200() with commits from DRUPAL-6--1 branch; fixed update errors due to duplicate data in Drupal 5 files table.
- #619150: Image attach views filter fails on PostgreSQL; use "IS NULL" not "ISNULL()" by kotoponus: Fixed image attach views filters SQL for PostgreSQL.

This release should fix the "Duplicate entry 'xxx-thumbnail'" SQL error that updating from 5.x-1.x to 5.x-2.x was producing; see #207557: update 5-1 to 5-2 gives user warning: Duplicate entry '611-thumbnail' for key 1 query in image_update_5200 for more details.