update matrix.py and polynomial.py

matrix.py
* Add support for 2D-List input for Matrix class constructor
* Add support for matrix multiplication in __mult__ in Matrix
* Add support for scalar addition in __add__ in Matrix
* Add get_col() and get_row() in Matrix for getting specific rows and
columns
* Flush out skeletons for __sub__, __div__ in Matrix, fliplr(), and
sym()
* Add zeros() in unimath -> returns m x n list of zeros
* Add listsum() in unimath -> returns the cummulative sum of elements in
a list
* Add list * list multiplication to mult() in unimath -> returns the
element by element multiplication of two lists
* Rename sum() and geom() in polynomial.py to polysum() and polyprod()