Start code instrumentation for benchmarking purposes.

Added a library to perform stopwatch measures on total running time and total
communication time.
Improve code instrumentation capabilities.

Now the metrics are output to a fixed file instead that on stdout.
Also, all time metrics are output in ms instead of s.
A new metric has been introduced, that is, the percent ratio between
computation and communication time.
Pass the benchmark output file as a command line parameter.
Reimplement final hull reduction scheme.

Now the functionality is implemented with an omega network that mimics the way
the original MPI_Allreduce works, i.e. by performing the reduction in a
logarithmic fashion, then broadcasting the value found.
Coordinates are now represented by long long ints.

Since long ints size is dependent on the architecture. Long long are instead
always 64bit (which is what we want to avoid overflows).
Don't sync git tree on the Power7.
MOAR DATA.

Update Makefile so to try the algorithm with more configurations.