CPU outputs have been improved in the main routines

We added the following options in the Makefile
DETAILED_CPU_OUTPUT_IN_GRAVTREE
DETAILED_CPU_OUTPUT_IN_HYDRA
DETAILED_CPU_OUTPUT_IN_DENSITY
DETAILED_CPU_OUTPUT_IN_STARS_DENSITY
DETAILED_CPU_OUTPUT_IN_CHIMIE
In the corresponding files, more info on the CPU needed
is now saved in timings.txt