Added command-line argument --noWidgets to yarpview-gtk and yarpview-qt

I have modified both yarpview-gtk and yarpview-qt in order to accept the argument `--noWidgets`, with which the yarpview is created with no titlebar, no menubar, and no statusbars (only the view). It saves approximatively 40% of space for a standard 320x240px yarpview, and it can be useful with cramped desktop space or a crowded workspace with a lot of yarpview(s). The window loses its resize-ability and there is no close button any more, but it can stiil be closed by `alt+F4`, `ctrl+C` or `gyarpmanager`.

I understand that the name of the parameter is not that great, and I'd be more than pleased to change it if you choose a better one. :+1: