cmdutil: extract closure that performs the actual export formatting This simplifies things a little by making the actual act of turning a revision into patch data a single function. After this, adding formatter support to `hg export` should be much simpler.

cmdutil: use a generator expression instead of a list comprehension

cmdutil: rename template param to export to fntemplate It's actually a template for the filename, not a formatter template.

cmdutil: comprehensively document the interface of export I want to make some improvements here, but in order to make future patches easier to review I want to document the current state of the world.

tests: hide warning from test-xdg.t The test-xdg.t test uses the system hgrc because it unsets HGRCPATH. If the system has an extension enabled that doesn't work with the development version of Mercurial it prints an 'extension failed to load' warning. Let's just hide that by piping stderr to /dev/null.

policy: define C module versions individually This allows us to bump the version for a single module without changing all of them.

repoview: rename '_getdynamicblockers' to 'revealedrevs' (API) Recent mailing list discussion made me realised we could clarify these. We make the function "public" to encourage extensions to wrap it and we use a more explicit name that mirror "hideablerevs".