Add notes about configuring a merge program

Update copyright year and change to range

Use patch.patch() when checking for patch availability. The test is closer to what we want to know. It also makes sense when you deal with patched versions of patch() as most people do under win32.

Merge with crew

Fix find_in_path not including some file extension logic under win32. Windows shell resolves utility path by combining PATH, the utility name and a set of file extensions from PATHEXT.

Fix bad reference to RepoError in import command

Refactor commands.serve to allow other commands to run as services. This introduces a new function, cmdutil.service.

Merge with stable

Do not automatically rename an atomicfile if a write to it has generated an exception.

merge with stable

Make copy --after work for files that have been hg added.

When reloading the dirstate, recompute ignore information if needed.

dirstate: speed up write by 50%.

dirstate: make parents() faster. This allows localrepository.status() to avoid reading all but the first 40 bytes of the dirstate in the common case of running "hg status".

localrepository.status: only acquire wlock if actually needed. This speeds up the common case of not needing to update the dirstate, and avoids the need to reload and parse the dirstate "just in case".

util._matcher: speed up regexp matching. In 4babaa52badf, Benoit made a change that substantially slows matching when a big .hgignore file is in play, because it calls into the regexp matching engine potentially hundreds of times per file to be matched. I've partly rolled back his change, so that we only call into the matcher once per file, but preserved the ability to report a meaningful error message if there's a syntax error in the regexp.