Add/Amend RS+ part volumes on small enough parts

[Poodmund]

Use the mod KSP Part Volume to generate volumes for all parts 2700L and less as the most volumetric Vanilla part that can be stored comes in at 2400L. KSP Part Volume adds an additional volume for packing etc. most are around 10-15% more voluminous than their mesh.

[Poodmund]

I queried the changes with CanOmer on the KSP Forum, who raised the request, and they liked the post so I guess its good enough. 😀