Fix 'SamsCAuth' integration; fix a few user-interface strings

[nfreear]

..

• [x] — template string: Report >>> Feedback (Simon C briefing),
• [x] — template string: Assignments >>> My assignments (Simon C briefing),
• [x] — User controller: make error messages more user-friendly (again),
• [x] — Login controller: SamsCAuth user-role fix,
• [x] — app/config PHP template: set draft_maxlength_chars (after Simon C briefing) — 30,000 characters,
• [x] — ensure the users.last_visit database field is set on login,
• [x] — new DB field, users.visit_count INTEGER — increment on each login,
• [x] — fix handling of database connection errors.

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[iet:10302188][iet:10302190]