Database migration adjustments

Drafts have no version

Update assignments when patterns are added

move all constants to their own class

Check for existence

Save published status in own field

Cleaner access to revision data

Working check whether current user may see not only published revisions

WIP Show only published revisions to users without publishing privileges

More info in publish banner

Admin interface and required code cleanup

Simple syntax

Use a regular struct schema instead of custom table

Publishing not quite working yet

WIP