replace LBQ with LazyFetcher

LazyFetcher is the same as LBQ, but with multiple pools to avoid race
conditions with the kind of multithreading AnyEvent emulates.
fix input decoding in MwAPI/{LLAPI,Request}.pm
Source/FromMediaWiki.pm: adapt to interface changes in Page::StdPage
Pipeline.pm: can't use MCE, too many shared variables
(minor) Pipeline/Buffer.pm removed: not needed at last