gdl: update to 3.28.0.
Based on mef's wip/gdl.
Changes in 3.28.0
* bgo#791913 - Convert Latin-1-encoded characters to UTF-8 (Ting-Wei Lan)
* Translation: da (Ask Hjorth Larsen)
Changes in 3.26.0
None
Changes in 3.25.91
* Remove ome run time warnings (Sébastien Granjoux)
* Convert various source files to UTF-8 (Emmanuele Bassi)
* dock-object: fix gtk-doc comment for dock signal (Ting-Wei Lan)
* Translation: eo Kristjan Schmidt
* Translation: fur Fabio Tomat
* Translation: da Alan Mortensen
Changes in 3.22.0
* Really enforce GDL_DOCK_ITEM_BEH_CANT_CLOSE (Lukas K)
* Translation: oc Cédric Valmary
* Translation: fr Alexandre Franke
* Translation: pl Piotr Drąg
Changes in 3.20.0
* No changes
Changes in 3.18.0
* Use "resize" property and fix a bug in panel widget (Vladimir Motilenko)
* bgo #751239: fix preview window color (Lukas K)
* bgo #729325 - Set type hint of dragged-out windows to TOOLBAR (Lukas K)
* Translation: ca Jordi Ma
* Translation: pl Piotr Drąg
* Translation: pt Pedro Albuquerque
Changes in 3.16.0
* Translation: bs Samir Ribic
* Translation: sv Anders Jonsson
* Translation: tr Necdet Yücel, Muhammet Kara
* Translation: eu Inaki Larranaga Murgoitio
Changes in 3.14.0
* No changes
Changes in 3.13.92
* Translation: nb (Kjartan Maraas)
Changes in 3.12.0
* No change
Changes in 3.11.92
* Fix build using C++11 (Ryan Lortie)
* Fix valgrind warnings (Sébastien Granjoux)
* Update FSF's address (Daniel Mustieles)
* Translation: zh (Wylmer Wang)
* Translation: de (Christian Kirbach)
* Translation: sr (Мирослав Николић)
* Translation: lv (Rūdolfs Mazurs)
UnifiedSplitRaw
