Thanks for the idea and most of the implementation to Klaus Koch
Backs revisions() and filerevs() with DAG walker which can iterate through
arbitrary list of revisions instead of strict one by one iteration from start to
stop. When a gap occurs in a revisions (i.e. in file log), the next topological
parent within the revset is searched and the connection to it is printed in the
ascii graph.
File graph can draw sometimes more connections than previous version, because
graph is produced according to the revset, not according to a file's filelog.
In case the graph contains several branches where the left parent is null, the
graphs for each are printed sequentially, not in parallel as it was a case
earlier (see for example the graph for README in hg-dev).
While this situation should never under normal use, some real
life repos sometimes contain such changesets (older hg versions,
broken rebases, etc...)
hgweb was displaying an "Internal error" in this case, and graphlog
displayed a redundant branch all the way to null: it does not cost us
much to just ignore this extra parent when constructing the DAG.
When issuing `hg pull -r REV` in a repo with no common ancestor with the
remote repo, the message 'requesting all changes' is printed, even though only
the changese that are ancestors of REV are actually requested. This can be
confusing for users (see
http://www.selenic.com/pipermail/mercurial/2010-October/035508.html).
This silences the message if (and only if) the '-r' option was passed.
The glog command didn't emit header and footer from the style, as demonstrated
by "hg glog --style xml". Asciiart combined with xml markup hardly makes sense,
but header and footer might however be useful for adding for example html pre
tags around the graph.
