Xamarin Changes

For issue https://github.com/fsharp/fsharpbinding/issues/96

I have merged the Xamarin Changes in as well as a couple of script fixes.

Tooltip intellisense doesn't work due to API changes.  
I haven't had time to look into this in any detail, the gist of it is the ITooltipProvider is now an abstract type rather than an interface so its a matter of adding the overloads required.