[patch] pear revert command

Hi all, I've got a patch for the new pear revert command. The patch is against CVS for php-src/pear, I'd love if people could take a quick look at it if there is time. The process turns out to be incredibly complex, in order to catch all error conditions, but basic revert is very simple, and is working. The thing is, there aren't any packages that I know of which use the "lt", "le" or "not" dependency relation yet, so there is no way to reliably test the dependency checking code yet :). As soon as I can set up a few fake packages to be used for unit tests, that problem will go away. If the patch basically looks good, I'll commit it so that rigorous testing can be done more easily. I've tested it by installing Net_URL 1.0.9 and Net_DIME 0.2, upgrading both, and then using pear revert individually and with both on the command-line, as well as verifying that pear revert will only revert once. Greg