Using approximations in Colebrook function.

In tests with a full engine, It is increasing the simulation speed
another 8 %.
Faster PutLabel.

The labels are only initialised once.
Using approximations in Colebrook function.

In tests with a full engine, It is increasing the simulation speed
another 8 %.
Merge remote-tracking branch 'refs/remotes/Private/master-unix'
Corrected CXX flag for C++11 compilation
Variable number of threads for FlowIndependent.

We are using a maximum of 3 threads, but degrading to 2
or 1 if omp_get_num_procs() or OMP_NUM_THREADS say so.
Sove problem for rc files in windows
Correction of bugs.
New maximum compressor ratio to interpolate.
Damping in the compressor solution