[PATCH 0 of 8] Move bookmarks extension to core

[dsp at php.net]

Move the bookmarks extension to core and simplify bookmark behavior.

This is the first version of a patch series to move bookmarks to core (Thanks
to the recent Mini Sprint).

1. Move bookmarks to core
The series moves the hg bookmarks to command to core and removes the bookmarks
extension.

2. Remove track.current and make bookmarks behave like track.current = True
As mentioned on the mailinglist, it is a bad idea to not have a current
bookmark. There is always a current bookmark now.

3. pull behavior changed
Instead of pulling a specific bookmark from a remote repository, hg pull
now pulls all remote bookmarks. I think that we consider bookmarks on a remote
repository always public as there is no notion of a private bookmark. It is also
closer to the behavior I like to have to support feature branches using
bookmarks. hg pull still pulls only a specific bookmark using the -B option.

4. bookmark support for clone
clone now always pulls all bookmarks from a repository. If you like to clone a
repository, you probably (as the name suggests) want to have a 1:1 copy,
including bookmarks.

I did not yet restrict the possible characters for bookmark names. Maybe we want
to restrict the available character for names.

Discuss :)

Regards
David