Split giant Bot into RecordChanger objects

[bencomp]

I like the pipeline design (do x1 first, take the result and do x2 to it, take that result and do x3 to it, etc.), but these record-changing functions should be modular (think 'helper bots') with VacuumBot dividing the work over the modules.

E.g. EditionFormatCleanerBot, EditionAuthorUpdaterBot, EditionPaginationCleanerBot.

Some modules are more generally applicable than with VacuumBot alone.