Set title attribute for all unclear frontend spots

Places where this should be done (list is not done, should be extended)

• buttons without labels
  • Sidenav toggle (the hamburger icon)
  • the notification dialog button in the navbar
  • the account menu trigger button in the navbar
  • the delete button in the inline crud list (this was there some time ago, probably got lost during the crud refactoring)
  • left right navigation in calendar
  • floating action button in calendar
• PersonChip should show fullName in tooltip (iff shortname is displayed in chip but fullname is also supplied)