Created separated directories for C++ and CUDA implementations
test
C++ base version implemented. A clean, simple, short file that intends
to reflect the algorithm in the clean way.
Added the OMP version of the C++-base implementation.
renamed the files to include a number indicating the order in which the
improvements has been added
1) Organized C++ implementations. Now there are 3 stable versions and one experimental version:
   * "dev" version (experimental)
   * "base" version (simplest)
   * "omp" version ("base" version, but using open mp)
   * "hybrid-float-double" version (version that tries to compute using float and re-computes using double when the result is too small)

2) Simplified the script for benchmarking... Previous script was too much complete... So complete that every time a benchmark was going to be done, it was necessary to spend a lot of time re-reading and re-understanding this script. It has been simplified a lot to avoid this situation in the future.

3) Added the results of the benchmarking of the float version of cuda implementation, together with an analysis of the results
Now it is possible to use many different implementations (float, double, quad, etc)
very easily. This change allows to easily implement the hybrid float-double that
showed to be faster than the double-only approach.
Implemented hybrid double-float version in CUDA
Benchmarks for the hybrid version.
Cleaned up the Makefile and C++ implementation of the float-double hybrid.