[Development] Move math3d from QtGui to QtCore

[Oswald Buddenhagen]

On Wed, Jul 04, 2012 at 06:27:19PM +0100, ext Laszlo Papp wrote:
> I would like to propose to move the math3d folder with all the
> portings of course to QtCore from QtGUI in Qt5. The reason is simple:
> I have recently started to work again on QtAudio3D, and I realized
> that, I would need such things like QVector3D. Surely, an 3D audio Qt5
> add-on should not depend on QtGui since wrapping coordinates and so
> forth are basically a core feature to me. I have already started
> writing the change, but it is unfinished yet.
> 
moving the math3d classes to a more prominent place instantly prompts
the question: why don't we just use Eigen?
(yes, we had that discussion internally already. it was all "but we need
only ..." and "let's be pragmatic" blah blah.)
(don't bother replying to this before reading eigen's licensing FAQ.)