[PATCH 0/6] Clean up reply's encoding story

[Austin Clements]

Jeff Stedfast's email about gmime-filter-headers.c possibly being
unnecessary with GMime 2.6 (quoted in id:87bo56viyo.fsf at nikula.org)
sent me on a wild goose chase that led to this patch series.  It
turned out that we *did* need gmime-filter-headers for what we were
doing in the reply text format, but what we were doing made no sense.
Patches 1 through 4 are simply the documentation and tests that I left
in my wake and are harmless to push.  Patch 6 is my conclusion that
how we were handling header encoding in the text reply format made no
sense.  Patch 5 is a step toward patch 6, but makes sense on its own
even if we decide against patch 6.