Friendlier Related tab+solution

Making the Related tab simpler and more useful for what people mostly use it for:

1. Make each section into its own submenu tab, and implement them as cards. Designing in-place here:
   
   • Cardtype+*context
     
     • type+*rform: +type cards, +*tform (on type cards), link to create another (default on Cardtypes)
   • Role+*context
     •  members:... — default
   • *account+*context (i.e., in Related tab of cards with account extension; default for them):
     • Role+*rform:  +edits and roles
   • *context
     • community+*rform: +tags, +editors, +discussion (default on other cards)
     • plusses+*rform:  plus cards, (plus parts? they're in footer...)
     • references+*rform: links and inclusions
     • (config): +*rform (on cards that can have one, and plus cards whose right part has one), +*edit, +*new, +*options (Pointers), +*table of contents (on richtext cards) this whole card will probably have to be from code for now
2. Use content rather than closed view, at least on some.
3. Add explanatory text about what each list means (see Related tab)

This ticket subsumes add role, member, editor to Related tab and User contributions.

Changes made as part of this:

*cards linked to -> links

*cards linked from -> linkers

*cards included -> inclusions

*cards that include -> includers