Avoid platform dependency with compiled code

Hello,

Recently we have seen an error when running devtools::document() in hub:

# in hub R version 4.2.1 (2022-06-23)
> pkgload::load_all("/esarchive/scratch/erifarov/git/cstools")

Error in dyn.load(dll_copy_file) : 
  unable to load shared object '/tmp/RtmpR0ftbE/pkgload102e8b72ef65ab/CSTools.so':
  libgfortran.so.3: cannot open shared object file: No such file or directory
 

The description of this problem is done here.

To solve this issue we could do:

• Remove the compiled file CSTools.so from the repository.
• Relocate the src/ scripts in order to not compile them when building the package.

Best,
Eva