[balsa/popover] (16 commits) ...Merge branch 'popover' of gitlab.gnome.org

[Peter Bloomfield <peterb src gnome org>]

Summary of changes:

  67c2508... Release balsa-2.5.9 (*)
  55094b1... meson.build: bump version (*)
  4e0c823... Fix a mailbox-threading bug. (*)
  616c9b8... meson.build: Do not enter endless loop (*)
  77aa595... meson.build: Use meson's "optimization" option (*)
  46d67b2... meson.build: Use dependency()'s capabilities (*)
  9538ac0... Display S/MIME and TLS certificate chains (*)
  5e04c8d... Updated Spanish translation (*)
  5053850... Fix handling of Multipart/Related (*)
  17b0085... Update POTFILES.in (*)
  e111ff3... Update Polish translation (*)
  3dc339c... Use strcmp() instead of g_ascii_strcasecmp() (*)
  d555ffe... Updated Spanish translation (*)
  5eb0835... Address book editor: do not crash (*)
  c4c633a... pref-manager: Use GtkPopover for "Add" options
  4d5c422... Merge branch 'popover' of gitlab.gnome.org

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