Various changes

- contributors shown on the event view (list of the organisation logos of users that have contributed through proposals)
- these link to the event history containing only entries from their organisation

- changes to the activity heatmap
- heatmap now dynamically changes the range on the graph based on the obtained values
- performance improved
- buttons to move back or forward in time on the calendar

- Attributes:
- warning for the user if he/she has selected the attribute category "targeting-data" or "attribution" as these could contain classified information
- UI improvements across most attribute and shadowattribute input views

- Updated cal-heatmap to the newest version