Lineup editor improvements

Some brief thoughts:

- 0.75 is too opaque for instrument options that aren't checked, it isn't clear which options are selected
- Sorting of people in lineup order, and instruments by yes/maybe/no should happen on the first load, and if requested by the user via a button
- The page should have more detail about the gig than just the title, should also include the date too, and possibly the notes as they can refer to lineups
- The secretary should be able to view and edit lineup admin notes, but not the lineup itself. This currently isn't possible, find a solution to make it possible (maybe in the signup summary thing?)
- Maybe the sections should be collapsible, it's a bit hard to find the important stuff currently amongst all the people?
- There are no links to anywhere, it should at least link to the gig summary, and possibly the gig diary too