[ticket/12169] Convert user_from to profile field location

Missing changes on memberlist view due to missing functionality

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[ticket/12169] Allow displaying profile fields on memberlist

We can not sort by profile field values atm. And also I'm not sure
whether this is possible at all.

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[ticket/12169] Add new option to display profile fields on memberlist

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[ticket/12169] Split mode==headline into it's own function

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Merge pull request #2010 from nickvergessen/ticket/12169

Ticket/12169  Convert location user field to profile field