Changes following turboencabulator's work

* preparing groundwork to remove external xml library and using QtXml.
Move add_executable from root CMakeLists.txt to ui/console/CMakeLists.txt

* preparing for Qt ui compilation.
Qt gui builds.

The gui has been ported to qt5 ( not much work thankfully )
Use QDesktopServices to open "http://boomerang.sourceforge.net"
Latest changes from turboencabulator/boomerang@6ec961abae9b3a86c276db71fc9c27fa07ea2550