hgext: add a simpler extension to enable obsolete on server

drop: divergence related code It is now in code

evolve: remove revset calls in warnobserror revset have serious performance impact in several case. The resulting code is a bit too complicated to my taste. I hope for much simpler implementation in core anyway.

evolve: drop "troubles" and "troubled" method now in core

test: drop rebase test We assume that the mercurial rebases tests suite is strong enough now.

doc: fix grammar, spelling, punctuation I restrained myself to making only changes that turn bad English into good English. There are still opportunities to improve, but other changes require some discussion and review. This change should be uncontroversial.

tutorial: fix grammar, spelling, punctuation I restrained myself to making only changes that turn bad English into good English. There are still opportunities to improve the tutorial, but other changes require some discussion and review. This change should be uncontroversial. The same changes had to be duplicated in both copies of the tutorial (hmmm); it's not clear which one is definitive.

[evolve] Drop useless filtered code

merge with filtering change (DO NOT USE WITHOUT FILTERING)

evolve: ensure evolve command run unfiltered

test: drop divergent test It is into core now

evolve: stop working around phase limitation Core is handling this part a bit better

fix punctuation

evolve: fix version message

test: more resistance to filtering changes