Created by: jcfr
@pieper Instead of a systematically re-initialization the
QWebChannel, this PR re-refactor the code introducing
qSlicerExtensionsInstallWidgetPrivate::initializeWebChannelTransport(QByteArray& webChannelScript) allowing both the base and derives classes to customize the WebChannelTransport initialization call back.
See also this documentation mentioning that only one WebChannel can be initialized only once per page. See http://doc.qt.io/qt-5/qwebenginepage.html#setWebChannel
This means that to evaluate python from a webpage loaded through a
qSlicerWebWidget, it is now as simple as doing
window.slicerPython.evalPython("print('hello from JS through python')")