Merge with BOS

Adapt commit to use file matching code. The code is slightly complicated by the need to commit all outstanding changes in the repository if no file names are given (other commands operate on the current directory and its subdirectories in this case). localrepository.changes has acquired an optional match parameter, to let it filter out include/exclude options.

Reduce the amount of stat traffic generated by a walk. When we switched to the new walk code for commands, we no longer passed a list of specific files to the repo or dirstate walk or changes methods. This meant that we always walked and attempted to match everything, which was not efficient. Now, if we are given any patterns to match, or nothing at all, we still walk everything. But if we are given only file names that contain no glob characters, we only walk those.

Fix documentation of -I and -X options. These options apply to all names, not just to directories. In other words, you can do something like this: hg add -X 'f*' '*.c' and it will have the effect of "add all files matching *.c, except those starting with f".

Move commands.forget over to using new walk code. With no names, it now recursively forgets everything, as is the default behaviour of other commands. And prints the names of all files it hasn't specifically been told to forget.

Fix performance regression in addremove command. When I rewrote addremove, I lazily put a call to repo.changes in, which was unnecessary and slow. This is a new rewrite, preserving the file name behaviour, but replacing the call to repo.changes with a walk, which is much cheaper, and avoids calls to os.stat on all but files that have probably been deleted.

Merge with TAH