Theming fixes: application theming, binding loop fix, auto-theming moved into MainView and it is applicable only on Ambiance and SuruDark, SuruGradient is no longer auto-themed. Fixes: https://bugs.launchpad.net/bugs/1213043, https://bugs.launchpad.net/bugs/1277647, https://bugs.launchpad.net/bugs/1330510, https://bugs.launchpad.net/bugs/1356779, https://bugs.launchpad.net/bugs/1389792.
Approved by PS Jenkins bot, Christian Dywan.