As I announced, here is a first version of the remapper.
I should warn that I did not really test it completely. at least, with no remapping rules, the input and output files are the same,a s by default, an icon with no remapping definition does not have its offset altered.
This means it is the responsability of whichever produce the mapping file to ensure every icon is defined. Otherwise, two icons may end up at the same offset and the statistics displayed will be wrong.
Next step: I need a gtkicon cache reader so that I can not only extract the exact list of icons, but the size of the metadata too so that algorithms output offset actually starting after the metadata. This is under the assumption that the size is not affected by the order of the icons. This is assuming too that there is two areas: The hash table and then the icons, not a mix of both.