started ResidualPhaseTensor class in pt module

Signed-off-by: LK <LK@uni>
ResidualPhaseTensor class: added definition - calculator: added multiplication of matrices incl errors

Signed-off-by: LK <LK@uni>
ResidualPhaseTensor class: added reading of 2 PT elemenst (arrays or objects)

Signed-off-by: LK <LK@uni>