graphmod: don't try to visit nullrev (issue3772)

log: remove any ancestors of nullrev (issue3772) For the special case, ":null" we remove the implied revision 0 since that wouldn't make any sense here. A test case is added to make sure only nullrev is shown.

help: add documentation for new template functions

changectx: fix the handling of `tip` We can not use `len(repo,changelog)`, it may be a filtered revision. We now use `repo,changelog.tip()` to fetch this information. The `tip` command is also fixed and tested Thanks goes to Idan Kamara for the initial report.

bisect: use changelog for iteration With changelog filtering, we can not use xrange anymore. We have to use the changelog to do the iteration. This way, the changelog excludes filtered revision and we can safely use what we iterate over. Without this changes, bisect crash with a traceback if there is filtered revision in the repo. Tests have been updated.

documentation: update to new filter names Changeset f3b21beb9802 change filter names but forgot some documentation updates.

largefiles: enhance error message to make it more i18n-friendly

merge with i18n

largefiles: fix largefiles+subrepo update (issue3752) Override updaterepo() instead of individual methods that may not be called for each subrepo. Add test. Based on patch from Matt Harbison. Changes the order of update-related messages (now largefiles comes before the global status).

debugsuccessorssets: fix typos in docstring