Port Workflow module to Drupal 6

This task is to update the Workflow module at
http://drupal.org/project/workflow from Drupal 5 to Drupal 6. The Workflow module allows the creation of different states for each node type (e. g. writing state, copy-edit state, evaluation state, etc.) and for different users to have access to the node according to the present state of the node (e. g. journalists in an early state, editors in the following state, copy editors after that, etc.) This is a very important module for big sites with large teams.

Each new major release of Drupal, we introduce new API features and changes
that can cause old modules to stop functioning. Modules need to be upgraded
with each new version of Drupal so that they are compatible.

To complete this task, work with the module maintainer to port the code to
the Drupal 6 API. Using the 5.x to 6.x upgrade page as a guide, make
changes to the 5.x version of the module so that it works under Drupal 6.

The final deliverable will be a patch against the HEAD version of the
module posted to the module's issue queue that has been reviewed and marked
"Ready to be Committed". See the "Code resources" section in the Wiki for
more information.

This task will take approximately 5 days.