Ogc 1785 submission windows

[BreathingFlesh]

Please fill in the commit message below and work through the checklist. You can delete parts that are not needed, e.g. the optional description, the link to a ticket or irrelevant options of the checklist.

Commit message

Org: Allow operlapping submission windows

Aloow overlapping of submission windows as long as they have a title.

TYPE: Feature LINK: OGC-1785

Checklist

• [x] I have performed a self-review of my code
• [x] I considered adding a reviewer
• [x] I have updated the PO files
• [x] I made changes/features for both org and town6
• [x] I have tested my code thoroughly by hand
  • [x] I have tested styling changes/features on different browsers
  • [x] I have tested database upgrades
• [x] I have added tests for my changes/features