Remove change history from preamble comments

[mlange05]

Many IFS/Arpege source files include a (sometime quite long) "history of changes" in the preamble comment. This information is nowadays easily obtained from the git history of the respective file, making it possible to remove these entries.

This issue was originally raised by @pmarguinaud in GPU adaptation additions. It pertains to the "Guidelines and recommendations" section. The original in-line comment was:

>>PM: suggestion: remove all history comments at the beginning of each routine; these can                                                                                                                                         
be obtained from git history.<< 

[RCHG]

Often the preamble of changes is useful to visualize and track back who introduce an specific improvement or implementation. Beyond the "acknowledgment" part (to persons and Institutions), it is important the possibility of contact with the specific developer to question about an implementation. The git history either in the online viewer of the repository or in the command-line is not providing the same kind of information (to my eyes, maybe I am not so well informed).

An alternative is to move the "modifications" to the end of the files rather than in the header to improve readability. Still, nowadays is very easy to "collapse" the comments so they are not noise anymore.