Initial support for WK2

The command line option '--webkit' allows switching between WK1 and WK2.
Add WK2 guards

Add missing WK2 guards and cleanup
Prepare for embedded QML use

No longer load external QML file + some cleanup
Remove browser.qml

qtbrowser has embedded qml support
Enable QML rendering

Add a view to create a scenegraph + small improvements
Integrate mouse acceleration patch

Initial port of the qtbrowser-pointer-acceleration.patch at https://github.com/Metrological/buildroot
Incorrect value WK2WebView::setFocus()

WK2WebView::setFocus() should set the 'focus' property to true
Improvements

Several improvements including initialization
Merge pull request #3 from Metrological/wk2

qtbrowser: add support for webkit2