YTVideoList: Fix loading on additional list contents
Make logger usable as a model element for listview.

This speeds up log displaying considerably
Improve YouTube web font loading

Previously the font was loaded using QML FontLoader element. The problem
with this approach was the font was loaded from youtube servers each
time the application was started. Enabling cache for QML
NetworkAccessManager did not fix this problem.
Improve loading of additional list contents.

Instead of using a bottom pulley menu automatically load additional
content when the user scrolls the page to the bottom.