Nested knots

[GMMULLER]

The user can use knots inside other knots (in and out fields) as if it was a layer. In that case, the final layer and thematic values of the knot are considered.

{
    spatial_relation: "INTERSECTS",
    out: {
      name: "layer1",
      level: "COORDINATES"
     },
    in: "knot2",
    operation: "AVG",
    abstract: true
}

[GMMULLER]

Also this should be implemented in a generic way so we can get rid of the knotOp that indicates if we are operating knots. In summary what should happen is:

• When using knots to compose other knots the last physical layer and the thematic output should be considered.
• If the user specifies an operation in the knot like (op = in - out) that is only allowed if in and out are either knots with thematic data (not pure) or layers that are out of the previous integration scheme (and therefore must have thematic data).