obsdiscovery: add an option to disable all obsdiscovery On large repository, computing the obshashtree can we as slow as resending everything. We give the option for people to opt out.

effectflag: better diff detection Improve the diff detection algorithm to have less false positive like in the case of a rebase that move the hunk in the file but the hunk stays the same.

effectflag: add a test for content detection Add a test for diff detection when the diff is different but only because of line numbers. The test is a append at the end of the file and we try to rebase it. We shouldn't detect a content change, it will be done in the next patch.

test: fix test-evolve-effectflags dates Mercurial < 4.3 don't have default date so add globs in the test-metaedit.t file.

test: fix metaedit tests by forcing dates Mercurial < 4.3 don't have default date so restore aliases forcing date in the test-metaedit.t file.

test: split test-stablesort.t in two This is the longest running test so we split it in two to help with parallel execution.

obsdiscovery: automatically pick protocol in a list This makes the code cleaner, clearer and more flexible. This also prepare the ability to disable obsmarkers discover entirely.

obsdiscovery: extract push-obshashtree discovery in a function This will help use to simplify the code.

obsdiscovery: directly use the 'only' revset for obshashtree The revset now exists and is fast. This remove the needs to hold a reference to "revs" in that code.

obsdiscovery: extract push-obshashrange discovery in a function This will help us to simplify the code. The code is updated to directly use 'outgoing' missing so that is no longer needs to access 'futureheads'.