amend: add noise in extra to avoid creating obsolescence cycle (issue3664) Obsolescence cycle are bad and should be avoided as much as possible. The current amend implemented touch changeset meta data as few as possible. This make is easy for amend to result in the same node than a precursors. We add some deterministic noise in extra to avoid this. In practice, the hex of the amended changeset is stored in 'amend_source' extra key.

changelog: extract description cleaning logic in a dedicated function The amend logic have use for it.

bookmarks: replace code-redundant comment with something more useful

bookmarks: remove another uneeded return

update: remove unnecessary argument check

grep: colorize all fields Colors were picked in accordance to GNU grep.

test-grep: add a test for -l

clfilter: remove use of xrange in revset For changelog level filtering to take effect it need to be used for any iteration. Some remaining use of `xrange` in revset code is replace by proper use of `changelog.revs` or direct iteration over changelog.

largefile: use `self` in repo method instead of `repo` Most method added (or overwritten) to repo by largefile works on `repo` instead of `self`. This currently works without trouble because `self` and `repo` are likely the same. However this is semantically dubious and this may cause issue for filtering. `self` may be proxy object different from the `repo` one. This changeset fix that and use `self` when applicable.

test: use proper subclassing in `test-issue2137.t`. To use changelog filtering on the repository, we plan to use "proxy" object that perfectly mock a repository but with a filtered changelog. Altering the `repo.commit` function using `extensions.wrapfunction` will prevent the logic to propagate to the proxy class by the mean of inheritance. We changes the extension to use subclassing as expectable.