1.4.0

This is the long overdue 1.4 release, which most importantly fixes some crashes occurring on many systems and updates the UI for new GNOME guidelines.

Thanks a lot for everybody who contributed, especially for your patience with this project. Your support has been amazing, most of the things changed here were provided by new contributors. I should have done this release way earlier, and originally it should have been out before GNOME 3.32. But as it sometimes goes real live and other projects kept me busy. Sorry for the long delay.

I originally wanted to include more in this release, but in the end it is more important to bring this release out and then focus on the future. I don't want to have such a long delay again.

Changes:

• feat: Move app menu into application Window (#391, #438)
• feat: New application icon following new GNOME icon guidelines (#114, #390)
• feat: Set window type hint to UTILITY (ensures window gets opened as floating
  on tiling window managers)
• feat: Show shortcut hint in main window (#234, #285)
• feat: Added Recorder, Video and AudioVideo to desktop files categories (#340)
• feat: Improved the error message shown on GNOME Shell recording issues
• feat: Provide more details in error reports
• fix: Fixed double free error after ffmpeg recording (#419)
• fix: Fixed building with Vala 0.46.1 (#501)
• misc: Raised minimum Gtk version to 3.20
• i18n: Updated translations for Basque, Chinese (simplified),
  Chinese (traditional), Czech, Dutch, Esperanto, French, German, Italian,
  Japanese, Lithuanian, Norwegian Bokmål, Polish, Portuguese (Brazil),
  Portuguese (Portugal), Russian, Serbian, Spanish, Swedish, Turkish, Ukrainian
• i18n: New translations for Japanese and Turkish
• build: New Meson based build (old CMake build is deprecated and will be
  removed in release 1.5)
• build: Autogenerate po/LINGUAS