Be more careful about freeing "default" profiles - don't free if it will be used in the destination image.
Move some functions over to Tags_EXIF_subst.cc.
Add tables for converting enum-style values to integers.
Add some more enum-style substitutions.
Use global table for EXIF key substitutions. Use a simple function to search case-insensitively.
Use a vector of pairs instead of a hash. We're going through every entry anyway, not using the hash/map search.
Change the IPTC and XMP key substitutions to function the same as EXIF.