Disable wide screen mode on mobile

This one is somewhat political - it disables widescreen mode (one page next to another) when running on mobile. When using some scaling parameters, I can get to widescreen mode and it feels odd on mobile. I presume it will be more frequent on devices with elongated displays, such as newer Sony Xperia. So, I suggest to disable it.

As usually wideScreen is bound to a formula, this MR drops the binding if mobile environment is detected.