grep: enable all-files by default (BC) This patch deprecates the `--all-files` flag and make the all-files behaviour as default. In test-grep.t, I removed '--all-files' from every command where it was used, to reflect that all-files behaviour is default and there is no change even after the removal. And other changes in test files are because of changed behaviour. Differential Revision: https://phab.mercurial-scm.org/D7000 .. bc:: `hg grep` now searches working copy file contents by default. We recognize this is a significant change from past behavior, but surveys of large bodies of users indicated nobody used (and almost nobody understood) the previous no-flags behavior of `hg grep`. The new behavior aligns with the behavior most users expected (including hg's maintainers), which also happens to be the behavior of `git grep`. Given that the old behavior was confusing to the point of being unusable, we were comfortable changing this behavior.