Added mergesort with tests

-Added Mergesort as algorithm
-Added functional testing for mergesort
-Added performance testing for Mergesort
-Added specific functions to generate sortable data
-Performance dump filename generation now incapsulated in a function
-Added defines to give filenames consistency
Added Fibonacci Exp by square with const mem

Added Exponentiation by squaring using constant memory, performance
tests and functional tests
Fixed CPU Cycle Measuring

Fixed the CPU Cycle measuring. Default is without RDTSCP, still need
to find a way to see if RDTSCP is locally available. Still it currently
works with RDTSC.
Removed <<<< HEAD
Improved time measurement

Used Chrono to get a better time measurement. To get significant
measurements it was neccesary to go to nanoseconds resolution.