Make mask finding configurable (random vs static)

[sigma-z]

I'd like to use your library without changing code.
But if I want to generate the same qr code images for the same text as input I have to change the constant QR_FIND_FROM_RANDOM. In my opinion the better solution would be to make it settable, may be by a method like QRmask::setMaskFindingMode() or so.
This would offer the possibility to generate the same qr code images without changing the code everytime you want to change the finding mask mode.