ruleup: purge duplicate requirements by default
Duplicate requirements may have crept into a requirement by the ruleset update code. Purge them from action enablers and from effects unless the --dirty option is specified.
v2: the previous version contain a last second "fix" that cased a memory leak.
Duplicate requirements may have crept into a requirement by the ruleset update code. Purge them from action enablers and from effects unless the --dirty option is specified.