Draw title bars more accurately in fake mode

Still not 100% perfect, but the title gradient is closer, noise texture is now drawn properly and things are layered correctly.

Deprecated title bar start/end colors since this API limits the gradient color stops to 2. The real gradient for active windows has 4. They should probably just be removed outright given that this a very small library but I'll leave that up to you.

Apple, just give us CoreUI. Come on now.