Given a segment, return the viewports that appear in that segment

[scholarsmate]

With a session and some viewports, given an offset and a length (a segment), determine viewports that appear in that segment. In the library this will be an iterator of viewports, and the RPC, it will be a vector of viewports.

[scholarsmate]

This can be done on the client side. I don't think there is a compelling reason to support this in the RPC layer or down in the library.