v2 patch converts the second category of functions. This conversion highlighted the lack of good examples in the str.split() docs, as well as some over and underspecification in the behaviour of the centering and justification methods (guarantees about object identity that don't hold for bytearray, failure to note that the default fill character is specifically an ASCII space - Unicode has more than one space type), so I also fixed those.

Added Guido to the nosy list - Guido, if you could cast your eye over this and at least give a +1 to the general approach, that would be great, otherwise I'll just go ahead and merge it some time after I finish converting the final category (which I expect will be no later than the PyCon AU sprints in early August, and potentially sooner)