Add a replace undo option

[racoltdev]

It's really easy to make a mistake with projectreplace that is not easily fixable. stdout from projectreplace should be more verbose, and it should be used in conjunction with a log file to perform projectreplace --undo, which holds a short stack of the last x number of actions. I need to come up with a safe way to delete log entries if they've been there too long without removing entries from large transactions before they're ready.