* extends the API to support serializing and deserializing of action_details and biotope_details
* renames biotope_extra_types into biotope_type_details on CompensationState model for convenience reasons and to match CompensationAction's action_type_details
* extends the detail view templates for all compensation related models to render extra CompensationState details as well
* reduces number of landing page news from 4 to 3
* improves .card-text in favor of .scroll-150
* improves .card font size
* adds support for DELETE method for all relevant objects
* improves get_obj_from_db functionality
* drops custom compensation logic for get_obj_from_db due to improvement of base method
* adds creation tests with minimum data for intervention, compensation, ema and ecoaccount
* fixes bug where empty geometry would not be created properly using the API
* reworks key fetching from POST data, so inproperly stated keys will lead to an error for the API user, instead of silently working and use default data
* adds some logical checks for deductable_surface of eco account creation using api
* fixes bug that would have occured on creating compensations via api
* writes test for sharing using the API
* fixes bug on frontend form where an exception occured on generating a new API token if no token existed, yet
* adds permission constraint (default group) for using the api in general
* fixes default-group-only behaviour for sharing-API, so users can only add new users and not removing them, as long as they do not have any other group membership like registration or conservation office
* changes 'ksptoken' to 'Ksptoken' to match CGI standard for http header keys
* adds support for PUT and POST of Ema
* moves set_responsibility() and set_legal() from Intervention API Serializer into proper Mixins where they belong to
* adds initialize_objects to an abstractmethod of the super class to be implemented in subclasses
* differentiates error messages if intervention does not exist or is just not shared with the user
* adds support for POST of new compensations
* adds shared_users property to BaseObject and Compensation to simplify fetching of shared users (Compensation inherits from intervention)
* extends compensation admin index
* modifies compensation manager which led to invisibility of deleted entries in the admin backend
* fixes bug in sanitize_db.py where CREATED useractions would be removed if they are not found on any log but still are used on the .created attribute of the objects
