VB -> C#: Incorrect class prefix for builtin date functions

[mrmonday]

Input code

Public Class Class1
    Sub Foo()
        Dim x = DateAdd("m", 5, Now)
    End Sub
End Class

Erroneous output

public class Class1
{
    public void Foo()
    {
        var x = DateTime.DateAdd("m", 5, DateTime.Now);
    }
}

Expected output

public class Class1
{
    public void Foo()
    {
        var x = DateAndTime.DateAdd("m", 5, DateTime.Now);
    }
}

Details

Product in use: e.g. VS extension

Version in use: e.g. 6.6.0

Built in date functions are in the DateAndTime class, not DateTime.

[GrahamTheCoder]

At the moment I think there's a very blanket attempt to make things use DateTime rather than DateAndTime. It was in a very early effort to head in the direction of #174
Perhaps a nice improvement here would be to check for the existence of a DateTime symbol, and fall back on using the DateAndTime one.