Function josh::history::unapply_filter

pub fn unapply_filter(
    transaction: &Transaction, 
    filterobj: Filter, 
    original_target: Oid, 
    old: Oid, 
    new: Oid, 
    keep_orphans: bool, 
    reparent_orphans: Option<Oid>, 
    amends: &HashMap<String, Oid>
) -> JoshResult<UnapplyResult>