Function to check C-C++ code

Added a function which compiles C and C++ code submitted by the student.

1) If compilation is successful, then the submitted code is tested using
   test-cases.

2) To test the function written by the student, a C++ file calls the
   function and passes the argument to the function. Then the function
   checks for the expected return value.

3) If the return value is as expected, then a different set of arguments
   are passed, and the output is checked.

4) If for all set of arguments the output is as expected then the student
   code is graded correct else the error is displayed to the student.