effectflag: allow to save effect of change in obsmarkers Obsmarkers lack a precious information, what are the changes between the source and the destination. This could be several thing: - The description has changed, with a amend -e for example - The parent has changed, with a rebase for example - The content has changed, with a amend for example - The meta, like the user, has change, with a amend -u for example Or any combination of them. We hijack the createobsmarkers in order to compute the modification and store the effect flag which is basically a bitfield of the changes list above and we store it in the metadata for the moment. The advantage of computing the flag just before creating the obs marker is that all commands will immediately be compatible and we can start working on the UI display of the flag. As a future optimization, the commands will be able to pass the flag directly or data to help computing them, for example amend knows if the description has changed or rebase now if the parent has changed, virtually removing the overhead. To start simple, this patch add the detection and storage of the effect flag when the description has changed. And hide it behind an experimental flag disabled by default 'experimental.evolution.effect-flags'. More flag will follow.

merge back with stable

readme: fix version number

next: prevent a color related crash when evolve This was not caught by test because they run color less.

prune: prevent a color related crash when the working copy is moved This was not caught by test because they run color less.

evolve: adding longer aliases for olog Novice users will likely find the longer versions more obvious to understand what they're doing (olog only makes sense once you already know what it does). Especially on the help page, "obslog" will be easier to find and make sense of.