draft : fix now save_att_params set /dev in .Rbuildignore file

[VincentGuyader]

fix issue #101

[VincentGuyader]

small modification, but a lot of test to adapt/correct :(

[statnmap]

Could you please write a unit test for this part of the code ?
Also, can you please make the change in the flat file (dev/flat_save_att_params.Rmd), and then inflate. As is, the flat file is not consistent with the R file and still uses {usethis}.
Thanks