[geary] (23 commits) Non-fast-forward update to branch wip/512-s390-redux

[Michael Gratton <mjog src gnome org>]

The branch 'wip/512-s390-redux' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  5879b91... Add extra debugging to Util.Avatar test case

Commits added to the branch:

  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' (*)
  f14b16f... Move WebKitUtil namespace to Util.WebKit (*)
  907d5b3... Update Turkish translation (*)
  4bc26c1... Update Turkish translation (*)
  6f1834d... Port JavaScript code from JS to JSC APIs (*)
  da6ac82... Move Geary.JS package into client as Util.JS (*)
  df8a96c... Clean up meson dependency lists (*)
  83309d2... Fix valadoc warning (*)
  7e9787f... Merge branch 'wip/jsc-migration' into 'mainline' (*)
  d05726d... Add extra debugging to Util.Avatar test case
  6f70225... Don't attempt to get the last initial if no other word

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