archive: add help examples

test-rollback: tinker a bit to make it easier to add more tests.

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).

util: fix finding of hgexecutable The version introduced in 89d9f92f6fdd would for example return thg (thanks to Mads Kiilerich for pointing to this)

log: add a usage note about --removed

log: rearrange the help text a bit

log: add some usage examples to verbose help

minirst: fix container stripping logic

share: allow trailing newline on .hg/sharedpath. This is extremely handy for those occasional circumstances where you need to edit .hg/sharedpath manually, since modern Unix text editors make it surprisingly difficult to create a text file with no trailing newline.

contrib: some support for named branches in zsh_completion (issue2988) named branches were not included for autocompletion in zsh. by adding _hg_branches and calling it from _hg_labels, named branches are now included when autocompleting many commands in zsh. support for completion of hg log -b was also added. there are possibly other cases where support needs to be explicitly added.