Logger add modules

Nothing really interesting here, I am fully adding the logger to GEAR (writing not reading). Therefore I have implemented the logger for the chemistry and star formation. I would say that the only interesting file is logger.c.

By the way, in the none/default module, I have a static variable that is not used in the writer, but we need it in the reader. What is it the best way to deal with this compilation error? Currently it is commented, thus I will not be able to compile the reader when I will implement it.

I have also realized that my 2 previous merge requests were not compiling and I am fixing them here (I do not what happened to me this week ^^").