3.6.1

Added:
▪ Development binaries now available on Bintray - https://bintray.com/martinrotter/rssguard/Development#files

Fixed/changed:
▪ Translations synced.
▪ Big code refactoring, fixed almost all usages of Qt deprecated code.
▪ Completely overhauled Appveyor/Travis build scripts which are now more reliable.