[balsa] (16 commits) Non-fast-forward update to branch threading

[Peter Bloomfield <peterb src gnome org>]

The branch 'threading' 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:

  31b79e2... Simplify threading
  61ea347... Limit use of LibBalsaMailboxThreadingType in src/
  ee517f3... Add UI for 'merge threads by subject'
  8fc8b07... Clear timeout source id in handler
  f5d1d0e... Check for valid msgno
  3203ecc... Simplify threading
  ce679e5... Clear timeout source id in handler
  20f8ce7... Check for valid msgno
  15e1fe7... Apply threading changes on 'Update'
  f8cb666... ChangeLog: Clean up  after rebase
  2427f87... Update Swedish translation
  e527baa... libbalsa/information: Use g_markup_escape_text

Commits added to the branch:

  589f78d... Update Brazilian Portuguese translation (*)
  2d99bab... Updated Danish translation (*)
  6a43d13... Fix crash listing S/MIME certificates (*)
  cf9d8bf... Updated Czech translation (*)
  80327c5... Update Swedish translation (*)
  1b06e7f... libbalsa/information: Use g_markup_escape_text (*)
  3e207a0... Simplify threading
  3b505e1... Limit use of LibBalsaMailboxThreadingType in src/
  de17d9b... Add UI for 'merge threads by subject'
  de4365e... Clear timeout source id in handler
  a9e2a7c... Check for valid msgno
  610ab3b... Simplify threading
  b773489... Clear timeout source id in handler
  00aeb45... Check for valid msgno
  e77ed39... Apply threading changes on 'Update'
  50d2100... ChangeLog: Clean up  after rebase

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