Redefine on delete cascades

[LKajan]

This is based on #452, merge that before this one.

Removed cascade delete from:

• codes.lifecycle_status -> hame.lifecycle_date

Added cascade delete to:

• land_use_area, land_use_point, other_area, line, other_point -> lifecycle_date
• plan_regulation, plan_proposition -> lifecycle_date
• regulation group -> plan_regulation, plan_proposition
• plan_regulation -> additional_information

Plan object tables has still on_delete=NO ACTION on their foreign keys to the plan table to prevent accidentally deleting the whole plan with objects.

Resolves #436, GispoCoding/arho-feature-template#193

[Rikuoja]

Really good! Maybe just combine the migrations or name them to explain why they are separate?

[LKajan]

@Rikuoja

Really good! Maybe just combine the migrations or name them to explain why they are separate?

I intentionally kept the commits small and logically separated.
I tried to name those before but forgot to give the name using the name= parameter of the make command. Now yhose should be named.

[LKajan]

Included also tests to check cascade deletions using both ORM and SQL.