Friction parameter is read at the top-level of YAML config file

[clement-moulin-frier]

Whereas it should be within an entity description (see example below).

Also, no error is raised when we define an entity field in the YAML that does not exist in the class datastructure. This is error prone (e.g. one could set friction there, as in the second yaml below, but currently it just ignores it and set the default value instead).

To check if there are similar issues for other parameters.

To define friction in the YAML currently we do:

friction: 0.25

entities_data:
  EntitySubTypes:
    - PREYS
    - PARTICLES

    PREYS:
      ...

    PARTICLES:
      type: OBJECT
      num: 200

Whereas we should do (if e.g. we want to have different friction in different entity subtypes):

entities_data:
  EntitySubTypes:
    - PREYS
    - PARTICLES

    PREYS:
      ...

    PARTICLES:
      type: OBJECT
      num: 200
      friction: 0.25