convert adds-changes dumps to single pass, pep8 and cleanup

* grab maxrevid in same pass as stub and page content generation
* regenerate index html after every run on a wiki
* toss separate index html and maxrevid update scripts
* pep8 cleanup, toss dead commented code, fix up usage message
* update READMEs to reflect how script now functions

Generating old dailies after the fact now works
(as opposed to generating only files that cover the entire
interval from the last working run to the current date)
Change-Id: Ibe6371bcf241e0a6b7f4ff7477370114a467a7f8