Changing distances to multimap to allow for multiple distances related to draft

UNLOCODE_to_vertex returns -1 if not found - adapted into parse_distances and parse_demands for coorect handling of errors.
skeleton for rotation variables
version 1.1.

Ports.csv rounded movecost to nearest integer.

specification of rounding TC rates to nearest thousand for high and low generation of cases.
wording rephrased
wording again