Allow users to register for a specific location on a drive

[dorodere]

The bus on each weekend doesn't just drive from A to B, but rather from A to C over D and then to B, leaving C out if no one registered for it. This is currently not possible to be expressed when registering, it would roughly include these steps:

• [ ] Adding locations
  • [ ] In the DB
  • [ ] In the UI as a new superuser control page
  • [ ] With the corresponding backend glue
• [ ] Correlating these locations to drives
  • [ ] By adding a new table to store these relations (this is a m:n relation)
  • [ ] Allowing the user to modify the exact location they register to, likely in the UI with a <select>
  • [ ] Displaying these relations on the registrations page for a drive
  • [ ] Adding a nice overview for a drive how many drive where

This is very involved. Likely it would be advisable to tackle #3 first and build a proper route and SQL interface separation.

[dorodere]

Oh and I forgot, for some drives (but not for all) it's also possible that users can enter on location C but most will enter on location A, which needs to be displayed as well.