[mono-vb] Overload changes

[Bernie Solomon]

I have a fairly extensive set of changes (a 1400 line diffs file)
which improve overload resolution, ParamArray handling and 
Optional arguments. I don't claim it is all correct yet but do 
believe behaviour is better. More tests pass than before -
though some "negative" ones now fail because they need
Strict On to fail. I've only been aiming at Strict Off checking
at least for things like Int->Short conversions.

I am not really sure what the goal is re handling of Strict so
whether my choice was correct.

Does anyone want to look at these before I check them in?
Or hold off for other reasons?

Thanks

Bernie Solomon