.hgignore

dirstate walking optimizations

The repo walking code introduces a number of calls to dirstate.map.copy(),
significantly slowing down the walk on large trees.  When a list of
files is passed to the walking code, we should only look at map entries
relevant to the file list passed in.

dirstate.filterfiles() is added to return a subset of the dirstate map.
The subset includes in files passed in, and if one of the files requested
is actually a directory, it includes any files inside that directory tree.

This brings the time for hg diff Makefile down from 1.7s to .3s on
a linux kernel repo.

Also, the diff command was unconditionally calling makewalk, leading
to an extra pass through repo.changes.  This patch avoids the call
to makewalk when commands.diff isn't given a list of patterns, cutting
the time for hg diff (with no args) in half.

Index: mine/mercurial/hg.py
===================================================================

\.orig$
\.rej$
~$
\.so$
\.pyc$
\.swp$
\.prof$
^tests/.*\.err$
^build/
^dist/
^doc/.*\.[0-9](\.(x|ht)ml)?$
^MANIFEST$
^\.pc/
^patches/
^mercurial/__version__.py$