[geary] (13 commits) ...Fix HTML, CSS, MIME and other artifiacts appearing in previews. Bug 714317.

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  330d263... Tidy up RFC822 default charset handling a bit. (*)
  deb0c41... Fix HTML, CSS and JS leaking into conversation list preview (*)
  1879ea8... Combine fetch and convo message codepaths for generating pr (*)
  ab18949... Don't generate a preview from non-text parts, e.g. multipar (*)
  821ae7c... Remove hacks for MIME part headers when processing preview  (*)
  f577e41... Workaround conversation message preview being cut off on wi (*)
  5b97efa... Add test case handling HTML entities when converting to tex (*)
  9757e6e... Synthesise PREVIEW field if HEADER and BODY were also liste (*)
  c2f0f14... Use preview synthesis when conversation list is refreshing  (*)
  fdb3c6c... Make to_preview_text() require UNIX (LF), not RFC833 (CRLF) (*)
  7654b16... Add unit test for Geary.RFC822.Message::get_preview. (*)
  f8c2a9a... Remove unnecessary return carriage in debug invokations
  1ad0228... Fix HTML, CSS, MIME and other artifiacts appearing in previ

(*) This commit already existed in another branch; no separate mail sent