references are now filled without new queries
not sure, if this is really effective, but it replaces the n+1 calls
with significantly less calls. Still need to step through all
workpackages several times to gather&fill all relations.

There is still a parent.children.size-query left, that needs to be
killed.

Either that, or get rid of these resolved&redundant references
alltogether and replace them with simple id's (e.g use project_id =1
instead of the redunedant project: {id: 1, name: "seeded project" ...}