C routines called as symbols and not name strings
 non-ASCII characters removed
 class checks doe with `inherits()`

class determination now with is(...) or inherits(...); calls to FORTRAN within C with string arguments platform independent

empirical structural functions for circular data described in the vignette register_new_layer_datatype.Rmd

C code doubled omp vs NOomp; extension of turning bands 2D to function as 3D (necessary for spherical models)