children should not have changes when data is set during parent instantiation

[nemophrost]

By have changes I mean calling .hasChanged() should not return true.

[nemophrost]

Not sure this is best place for solving the problem.

Another idea is at line 146, setting this[attr]._changed = {} for children (like what is done at the end of the Base constructor). This seems worse to me though because then it would be changing "private" attributes on something other than itself.

Yet another option could be to pass along the initial data for the child to _initChildren and exclude that from the data being set during instantiation.