convert: added bookmarks support in filemap When using the convert extension from a Mercurial rep. to subset it with filemap, the bookmarks are not copied. I fixed this by calling the base.get_bookmarks() from the filemap getbookmarks() instead of returning an empty dictionary. It should work also for other converters that implement getbookmarks() (like git). I don't see any drawbacks except that the bookmarks are always copied (not necessarily wanted all the times).