[geary] (19 commits) Non-fast-forward update to branch wip/778728-split-composer

[Michael Gratton <mjog src gnome org>]

The branch 'wip/778728-split-composer' 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:

  d4b335e... Tighten up flatpack manifest per flathub review comments.
  1dade66... Add some comments to nightly flatpak-builder manifest for c
  c1ef1b4... Install appdata to $PREFIX/share/metainfo, not the old appd
  fbb350e... Bump minimum library and vala version reqirements.
  a57753f... Remove GTK 3.20/3.22 source defines and the conditionals us
  c37465d... Remove set_label_xalign workaround and uses of it.
  a5d9a7d... Remove most of the remaining workarounds for earlier GTK ve
  b735695... Fix a compile warning.
  72b0cc1... Remove some uses of the deprecated GearyApplication.instanc
  10beedf... Give the insert inline image dialog a relevant title and bu
  a023fb8... Simply and update ComposerContainer interface and implement
  7d790f9... Split body editing code in ComposerWidget into new Composer
  459b325... Fix some spacing issues with the composer toolbar and attac

Commits added to the branch:

  b1e1d4c... Update Slovak translation (*)
  e0c3c22... Update Brazilian Portuguese translation (*)
  dc52e9a... Tighten up flatpack manifest per flathub review comments. (*)
  8df85fa... Add some comments to nightly flatpak-builder manifest for c (*)
  a83c6df... Install appdata to $PREFIX/share/metainfo, not the old appd (*)
  1e1b080... Bump minimum library and vala version reqirements. (*)
  c57cc28... Remove GTK 3.20/3.22 source defines and the conditionals us (*)
  592a526... Remove set_label_xalign workaround and uses of it. (*)
  bd7f2d1... Remove most of the remaining workarounds for earlier GTK ve (*)
  2e739b6... Fix a compile warning. (*)
  f708218... Remove some uses of the deprecated GearyApplication.instanc (*)
  4bb65d5... Update Unity specific workarounds (*)
  301ffa6... Fix attached message bodies not being loaded. Bug 788637. (*)
  456d3e9... Fix search loading spinner never disappearing when autosele
  c54d1e3... Give the insert inline image dialog a relevant title and bu
  3fc6d9b... Simply and update ComposerContainer interface and implement
  4b34891... Split body editing code in ComposerWidget into new Composer
  f364c6c... Fix some spacing issues with the composer toolbar and attac
  f81b557... Add new builder and source files to POTFILES.in.

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