purge: move extension into core mercurial
The motivation is simple: it's nicer to avoid gating basic
functionality.
To reduce the risk of people shooting themselves in the feet, `--confirm` is now
the default, unless the extensions is loaded..
For review of the body of the purge command, use this instead of what
hg/phabricator will show (the block of code is modified, not just
moved):
Differential Revision: https://phab.mercurial-scm.org/D9820
== New Features ==
* There is a new config section for templates used by hg commands. It
is called `[command-templates]`. Some existing config options have
been deprecated in favor of config options in the new
section. These are: `ui.logtemplate` to `command-templates.log`,
`ui.graphnodetemplate` to `command-templates.graphnode`,
`ui.mergemarkertemplate` to `command-templates.mergemarker`,
`ui.pre-merge-tool-output-template` to
`command-templates.pre-merge-tool-output`.
* There is a new set of config options for the template used for the
one-line commit summary displayed by various commands, such as `hg
rebase`. The main one is `command-templates.oneline-summary`. That
can be overridden per command with
`command-templates.oneline-summary.<command>`, where `<command>`
can be e.g. `rebase`. As part of this effort, the default format
from `hg rebase` was reorganized a bit.
* `hg purge` is now a core command using `--confirm` by default.
* `hg strip`, from the strip extension, is now a core command, `hg
debugstrip`. The extension remains for compatibility.
* `hg diff` and `hg extdiff` now support `--from <rev>` and `--to <rev>`
arguments as clearer alternatives to `-r <revs>`. `-r <revs>` has been
deprecated.
* The memory footprint per changeset during pull/unbundle
operations has been further reduced.
* There is a new internal merge tool called `internal:mergediff` (can
be set as the value for the `merge` config in the `[ui]`
section). It resolves merges the same was as `internal:merge` and
`internal:merge3`, but it shows conflicts differently. Instead of
showing 2 or 3 snapshots of the conflicting pieces of code, it
shows one snapshot and a diff. This may be useful when at least one
side of the conflict is similar to the base. The new marker style
is also supported by "premerge" as
`merge-tools.<tool>.premerge=keep-mergediff`.
* External hooks are now called with `HGPLAIN=1` preset.
* The `branchmap` cache is updated more intelligently and can be
significantly faster for repositories with many branches and changesets.
== New Experimental Features ==
* `experimental.single-head-per-branch:public-changes-only` can be used
restrict the single head check to public revision. This is useful for
overlay repository that have both a publishing and non-publishing view
of the same storage.
== Bug Fixes ==
== Backwards Compatibility Changes ==
* `--force-lock` and `--force-wlock` options on `hg debuglock` command are
renamed to `--force-free-lock` and `--force-free-wlock` respectively.
== Internal API Changes ==