MDR tested and adapted to multi-slice

[JoaoPeriquito]

• Multi Processing was removed (for now)
• MDR was successfully testd for single slice
• "_mdr" function was adapted to multi-slice
• MDR was successfully tested for multi-slice

Successfully tested means MDR of T1, T2, T2*, DWI, DTI, DCE and MT ran (and results appeared on the GUI) with a precision of 100 and a max iterations of 2 (for speed). Further tests will be carried out in a desktop with precision = 1 and max iterations of 5.