add --config global option. allows to set hgrc option on command line.
syntax: --config section.name=value
also add new test-globalopts to test all global options in one place.
(the addremove command is deprecated; use add and remove --after instead)
adding dir/bar
adding foo
dir/bar
foo
(the addremove command is deprecated; use add and remove --after instead)
adding dir/bar_2
adding foo_2
dir/bar_2
foo_2