cleanup: drop an empty section header

compat: drop some <hg-3.4 compatibility code The `hg commit` commands has a -i flag for ages now.

README: more update to prepare for pypi upload * mention the evolve.serveronly extension, * remove help related to topic into a different README file.

evolve: update the capabilities and commands name for obshashrange We makes is clear that these version are useful for earlier testing but they are not ready for any kind of real usage yet.

README: more change to have a pretty rendering on pypi We moves section around and fixes some markup.

MANIFEST.in: fix various mismatch check-manifest is no longer complaining

README: rework install instruction For both evolve and topic. The topic introduction is updated too.

README: rework the intro Less scary wording (similar to the wiki changes) and point to the user mailing list.

rangeobshash: minor cleanup of the obshash code We achieved minor speedup by delaying the hashing until we know it is needed.

stablerange: remove call to 'repo.revs' It turned out that the percentage of time spend parsing the revset string was two digits, so we compute de heads inline.