logcmdutil: unindent diff generator of changesetprinter Prepares for the next few patches which will make matchfn and hunksfilterfn always available.

logcmdutil: hold makefilematcher/makehunksfilter() by changesetpriner (API) This merges self.matchfn and self.show(matchfn) into self._makefilematcher, and does the same for hunksfilter. Because changesetprinter seems to have too many optional arguments, makefilematcher() and makehunksfilter() will be packed into one object by later patch.

log: pass ctx to makefilematcher() and makehunksfilter() functions This isn't important, but seems more consistent as changesetprinter.show() takes a ctx, not a revision number.