calculate execution time of functions

[Zineb-Ada]

The purpose of this PR is to allow users to calculate the execution time of their functions accurately and noiselessly. We have implemented two different functions to calculate this execution time, one with the bechamel library and the other with Current time (Sys.time). The interest is to facilitate the use of these functions. Indeed, the user only has to replace in “cobench-examples/example.ml” :

• “test_fact()” and “test_fibo()” by its functions
• The quota which is an optional parameter. The quota parameter is the maximum of time allowed. the user can adjust it by increasing or decreasing the time allocated by bechamel or he can also remove it because it is 1 second by default.
• The strings by the names he wants

[Zineb-Ada]

Thanks you for your return. I fixed it according to your recommendations.

[art-w]

Thanks a lot, this looks great!