Change method of finding files.

Instead of temporary adjusting IFS to handle filenames with spaces in it, use a slightly less ugly while-loop construction with the commands find and read.
Minor clarification with handling archives.

Don't assume zip is a final version's archive when processing. Instead check if the archive is the second (odd numbered) one being handled so that the tgz archive could be too.
Use unzip when available.

Tar can give problems when used for unzipping (using the current flags anyway). For now use unzip instead if possible.