Extend archipelago bird census

[mikkohei13]

This epic contains tasks needed of speculated for archipelago bird census after it has been taken into use.

• Summary observation form
  • MAYBE: Visit count / käyntikertoja: integer. For old data.
  • MAYBE: Date fields: list of 0...n date begin and date end -pairs. None of these are mandatory. For old data.
• Old data import, unknown how responsibility should be divided