Add an overload for GetFontSize with a float parameter to IFont

[Ven0maus]

Nice to have:

public Point GetFontSize(float size)
{
	return new Point((int)(GlyphWidth * size), (int)(GlyphHeight * size));
}

[Thraka]

Thought about but I don't think it's really useful to add to the interface. The easiest way to do that would just be to do this in your own code:

Point fontSize = font.GetFontSize(Sizes.One) * floatSize;