feature request: print LB/PL/PU/SM tags only in @RG header line

[eboyden]

Is there a means to only print the LB / PL / PU / SM tags in the @RG header line along with the ID tag? As far as I can tell they are automatically printed to every line along with the RG tag, which produces files that are larger than necessary, and there is no way to disable this behavior. Every other aligner I've used only prints those tags to the header, and they are linked to individual reads via the ID / RG tags.