3.20.0
======

* Improved links for the platform overview (Alexandre Franke)
* Clarifications and improvements to the programming guidelines (Philip
  Withnall, Sébastien Wilmet)
* Typo and small fixes for the optimization guide and HIG (Anders Jonsson)
* Use CC-BY-SA 4.0 for the platform overview (Ekaterina Gerasimova)
* Updated translations:
  cs      (Marek Černocký)
  de      (Mario Blättermann, Christian Kirbach)
  el      (Tom Tryfonidis, Γιάννης Κουτσούκος)
  es      (Daniel Mustieles, Javier Mazorra)
  ko      (Seong-ho Cho)
  sv      (Anders Jonsson)