K-way merge sort with k = 2, 4, 8
Interface changed to "int externalSort(int fdInput, int fdOutput, uint64_t memSize, unsigned k)"
Function used to test ascending output file is "int testExternalSort(int fileToTest)"
Output of externalSort is always written to "outputFile"
externalsort can be run via the command line using the command syntax "./externalsort "