Add a small allocations counter in SMPI.

Add a small allocations counter in SMPI.
With smpi/display-analysis, it can display the total memory allocated by malloc/calloc calls intecepted by SMPI.
It outputs at the end of the simulation the largest one, its address, and the number of times it was called, and hints to use sharing options on it.
To avoid too many globals, and singletons, I used the namespace smpi::utils to regroup all of these analysis tools. Please tell if this is awful C++ :p