Update and rename outputdatearray.c to outputdatarray.cpp

The assignment has this filename. Also, pass by reference only exists in C++, so going to change all files to .cpp
Update and rename outputviapointers.c to outputviapointers.cpp

Pass by reference does not exist in C, so changing to C++
Update and rename sortbypointers.c to sortbypointers.cpp

No pass by reference in C, changing to C++
add README.md
some comment blocks
rename to cpp
fixing merge