Review: oiiotool with image sequences

 Allow oiiotool to loop over image sequences (frame number ranges) -- long requested by a number of people.

Image sequences are specified by having filename arguments to oiiotool use either a numeric wildcard (designated by '#') or an explicit numeric range (designated such as '1-10#').  In effect, this will execute the oiiotool command several times, making substitutions to the sequence arguments in turn.  For example:

        oiiotool big.#.tif --resize 100x100 -o small.#.tif

if there are files big0001.tif, big0002.tif, and big0003.tif, will be the equivalent of having issued the following sequence of commands:

        oiiotool big.0001.tif --resize 100x100 -o small.0001.tif
        oiiotool big.0002.tif --resize 100x100 -o small.0002.tif
        oiiotool big.0003.tif --resize 100x100 -o small.0003.tif

The following is also equivalent:

        oiiotool big.1-3#.tif --resize 100x100 -o small.1-3#.tif