Sub groups

it would be good to be able to add subgroups inside of groups.

I would like to be able to have Framing as a group.

under that I would like to have framing tasks listed so they all show up on the proposal

Then I would want to have a item called framing materials as a subgroup. i would have all the individual materials in the subgroup. on the proposal though the client would just see Framing materials.

This would be very useful for most groups. like roofing, siding, tile, etc.