Enable shortenIDs to recycle existing IDs
Created by: nthykier
This patch enables shortenIDs to remap IDs currently in use. This is very helpful to ensure that scour does not change been "optimal" and "suboptimal" choices for IDs as observed in GH#186.
Closes: #186 (closed) Signed-off-by: Niels Thykier niels@thykier.net