Gives every user up to one role in each of three buckets, so the roles that different plugins add stop competing for a single slot.
The Add User and Edit User screens show one select per bucket, and the users list shows one column per bucket. The site role uses WordPress’s own role select, so core’s checks keep working. The forum role is saved through bbPress’s own handling. The shop role is restored after WordPress resets a user’s roles on save, and is carried through multisite invitations and signups. A bucket is hidden on any site where the plugin behind it is not active.
Which roles belong to the forum and shop buckets can be changed with filters.