Would be nice to be able to edit aggregates. Also +/- graphs

[dmaone]

delete/create is cumbersome.

by "+/- graphs" I mean bits_in goes down from zero, bits_out goes up.

http://oss.oetiker.ch/rrdtool/gallery/ has examples - like http://oss.oetiker.ch/rrdtool/gallery/nbar_optical_com_pe.png