Changelog and localization update.

Adding package repository link.

Ubuntu 1.53.0 Launchpad release of 5 current distros (except Trusty) …

…done.

Autolinking and macOS updates pull request #1255 from dvorka/dev/1.52.0

Ensuring that editor keeps focus when live preview is enabled #1214

Merge branch 'dev/1.50.0'

Updating Launchpad release version.

Brew vs. system Qt for WebEngine.

Updating changelog for 1.48.3 release

Improving aptly script.