symtom and tag - removing fix

http://stackoverflow.com/questions/7917259/nhibernate-removing-from-collection-vs-association-and-cascading-styles
- nhibernate 2 way while saving as well as removing

http://stackoverflow.com/questions/302720/how-to-delete-child-object-in-nhibernate
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http://stackoverflow.com/questions/4864115/fluent-nhibernate-mapping-is-set-to-alldeleteorphan-but-is-still-trying-to-null
- AllDeleteOrphan()

http://ayende.com/blog/1890/nhibernate-cascades-the-different-between-all-all-delete-orphans-and-save-update
- cascades description