Mercurial 5.3 release

This is an overview of the 5.3 release.

1. New Features

Windows will process hgrc files in %PROGRAMDATA%\Mercurial\hgrc.d.
The Phabricator extension will read .arcconfig in the repository root to assign
- the phabricator.callsign and phabricator.url properties, if available. This file will override the settings in the global or user level config files, but is itself overridden by the config file for the repository (issue6243)
Accept explicit -r 'wdir()' when adding new bookmarks (issue6218)
hg import has a new --secret option for committing with the secret phase.

The LFS extension adds --no-lfs to the verify, so that it won't attempt to
- download missing blobs as part of the process.

The indent() template function was documented to not indent empty lines,
- but it still indented the first line even if it was empty. It no longer does that.
Avoid setting both parents to the same commit in some cases when evolving a merge (issue6098)
Avoid spurious warnings with hg verify --verbose when there are renames in obsolete revisions (issue6172)
Check for unfinished ops when using the experimental in-memory rebase (issue6214)
Avoid corrupting dirstate if files are modified while the editor is open for an amend (issue6233)
Ensure reviews are posted to Phabricator in topological order, regardless of the order specified on the command line (issue6241)

Changed bundled config file location in Windows .exe installers to hgrc.d,
- from default.d. Consider using the new %PROGRAMDATA%\Mercurial\hgrc.d directory instead of the installation directory if you need to add custom config files globally.
File patterns for the fix configuration are resolved against the repository
- root, instead of cwd. This allows filesets to be resolved consistently, regardless of cwd.

Matcher instances no longer have a explicitdir property. Consider
- rewriting your code to use repo.wvfs.isdir() and/or ctx.hasdir() instead. Also, the traversedir property is now also called when only explicitdir used to be called. That may mean that you can simply remove the use of explicitdir if you were already using traversedir.
The revlog.nodemap object have been merged into the revlog.index object.
- n in revlog.nodemap becomes revlog.index.has_node(n),
- revlog.nodemap[n] becomes revlog.index.rev(n),
- revlog.nodemap.get(n) becomes revlog.index.get_rev(n).
copies.duplicatecopies() was renamed to
- copies.graftcopies(). Its arguments changed from revision numbers to context objects. It also lost its repo and skip arguments (they should no longer be needed).