Rename OHO → LOSH

In some places of the LOSH cosmos we still have (faulty) references to OHO. Those should be changed/renamed to avoid confusion.

• File/Dir Structure
• Instances in Configuration files
• HTML title of https://losh.ose-germany.de/ (also has the OHO Logo)
  • → rename to LOSH; we don't have a logo currently
• Database instances
• Mail address(es)