Merge branch 'bs/sendemail-tighten-anything-by'

The recently added feature to add addresses that are on anything-by: trailers in 'git send-email' was found to be way too eager and considered nonsense strings as if they can be legitimate beginning of *-by: trailer. This has been tightened. * bs/sendemail-tighten-anything-by: send-email: don't cc *-by lines with '-' prefix