perf: warm the cache after all transactions This is the simplest way to ensure the data are up to date.

perf: adds a cache to know if obsmarkers might affect a revision Phase information still needs to be thrown in the mix to compute the final information, but skipping reading the obsstore for most operation is a large win. Usage of this cache arrives in the next changeset.

perf: adds cachekey utility to validate changelog+obsstore content We adds more helper about cache key to prepare the arrival of a cache that can be updated iteratively (similar to branchmap cache)

perf: adds some cache key helper on the obsstore class This will be useful to allow validating cache depending on obsstore without parsing the whole obsstore.

compat: only install the better filtered message for mercurial 4.2 and above The helper function does not exist in earlier version.

evolve: update extension help I'm pretty sure there are some missing bits, but this cannot be worse than before.