namespaces: use named args for namespace api This is just a style change but makes adding new arguments more robust for callers.

namespaces: make the constructor into named args None of the arguments are truly optional but this makes adding future arguments more robust and perhaps optional.

dispatch: only check compatibility against major and minor versions (BC) Extensions can declare compatibility with Mercurial versions. If an error occurs, Mercurial will attempt to pin blame on an extension that isn't marked as compatible. While all bets are off when it comes to the internal API, my experience has shown that a monthly/patch release of Mercurial has never broken any of the extensions I've written. I think that expecting extensions to declare compatibility with every patch release of Mercurial is asking a bit much and adds little to no value. This patch changes the blame logic from exact version matching to only match on the major and minor Mercurial versions. This means that extensions only need to mark themselves as compatible with the major, quarterly releases and not the monthly ones in order to stay current and avoid what is almost certainly unfair blame. This will mean less work for extension authors and almost certainly fewer false positives in the blame attribution.