[geary] (13 commits) ...Merge branch 'wip/362-utf8-attachments' into 'mainline'

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  6a871c2... Remove Geary.RFC822.Part.get_effective_content_type (*)
  faf84db... Actually ensure the engine PartTest suite is run (*)
  2cb0a83... Don't munge Base64 encoded text parts when saving to disk (*)
  b955bc4... Hardcode PartTest's source encoding since it shouldn't chan (*)
  303fc9f... Update PreviewText.with_header to use convenience APIs (*)
  0697632... Update Buffer UTF-8 conversion APIs (*)
  8d6bffb... Consider US-ASCII to be UTF-8 for encoding conversion purpo (*)
  7cc3e66... Make adding MIME parts to a new RFC822 message async (*)
  3dc5476... Reduce blocking the main thread when sending email (*)
  d93ab35... Don't bother checking for best encoding for non-text parts (*)
  536120a... Minor code tidy-up (*)
  58afbc0... Fixb build warning (*)
  cfd1a61... Merge branch 'wip/362-utf8-attachments' into 'mainline'

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