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.

changeset:   0:9426b370c206
tag:         tip
user:        My Name <myname@example.com>
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     commit-1