Contact map x/y axis labels should reflect the positions of the sequence, not the number of the segment.

[dhrogers]

Users expect to navigate locations, etc. in terms of the sequence locations, not the ID of the segment (this is what appears to be the numbering on the axes at the moment.)

Convert these segment locations to sequence locations.

Possibly the only numbers that are needed are the beginning and end sequence ids (first and last positions, regardless of the zoom and pan of the contact map)