Add more type distinctions to Range

This allows a new type alias Section <: Segment representing a bounded
range of offsets.
Fix slotasset sql args after Volume condition changes

Introduced by 43b43b4
Merge remote-tracking branch 'remotes/origin/master' into angular
better record cross-index - still awful with volume/8
JsonRecord: remove quoting of string ids; include id in value
updating panels to take id->obj rather than arrays; tag panel functionality
Merge remote-tracking branch 'remotes/origin/master' into angular
tags panel functionality fully restored - after slot changes, revisit