made some changes in Matrix.h and Matrix.cpp

added exception class in Matrix to be thrown when we attempt to add a
Shape to an already occupied slot. Fixed the destructor so that it
doesn’t leak like crazy. Altered deleteRow to shiftDown the matrix and
then assign NULL to the top row.
It doesn't love me unless I commit everything.

You’re going to have to do the commenty thing in the includes. sorry.
it doesn’t love me. Feel free to ignore Tetris.1, as I assume you have
been.