filemerge: split the logic for finding an external tool to its own function This will be used by extdiff in an subsequent patch.

largefiles: simplify check for lack of path arguments Instead of checking for a partial merge by checking that the matches has no files and no patterns, check that it's not an always-matcher. Except for being shorter, it also catches the rare case of an exact-matcher with no files.

largefiles: shortcircuit status code also for non-matching patterns We currently shortcircuit the checking for large file standins if only patterns of type 'path' are given on the command line. That makes e.g. "hg st 'glob:foo/**'" unnecessarily slow when the only large files are in a sibling directory. Relax the check to be that it is not an always-matcher and that no large files match the patterns given on the command line. Note that before this change, only the latter of the following two would show the status of files in .hglf (since the -I makes match.anypats() true). After this change, they both display the status. This behavior doesn't seem correct, but it would be a separate change to explicitly filter out .hglf even in the shortcircuit case. hg st .hglf/$file hg st .hglf/$file -I .

largefiles: remove confusing 'or None' from predicate The match function that is overriden returns a boolean value, so adding 'or None' is both unnecessary and confusing.

largefiles: drop unnecessary setting of matcher._always In two very similar segments of code, an existing matcher is modified by changing its _files attribute through a map and a filter operation. Neither operation can cause an empty list to become non-empty, so a matcher that always matches can not stop always matching. Drop the setting of the attribute, so we don't unnecessarily prevent the fast paths to be taken where these matchers end up being used.

config: move mergetools configuration from contrib to default configuration The merge tool configuration is an essential part of a good initial user experience. 'make osx' installers and direct 'make' installation did not have merge tool configuration. Now they have. Note: The installer fixes for windows have been done blindly and might require additional changes.

config: introduce "built-in" default configuration settings in default.d This helps providing a more consistent user experience on all platforms and with all packaging. The exact location of default.d depends on how Mercurial is installed and whether it is 'frozen'. The exact location should never be relevant to users and is intentionally not explained in details in the documentation. It will however always be next to the help and templates files. Note that setting HGRCPATH also disables these defaults. I don't know if that should be considered a bug or a feature.

contrib: buildrpm checking of md5 checksums of downloaded Python and Docutils

contrib: update build defaults to latest Python and docutils versions Use Python 2.7.8 and Docutils 0.12 for Makefile.python and buildrpm (CentOS 5 rpms).

spelling: fixes from proofreading of spell checker issues