fix missing headers and issues with old FITS files for a22 and e3

[danehkar]

fix missing header issues and function declaration issues with gcc (GCC) 14.2.1 20240912.

relutility.h: declare functions in th header:

int is_densgrad_model(int rmodel_type, int xmodel_type, int ion_grad_type );

void get_version_number_nk(char** vstr, int* status);

rellp.c: add a missing header:
#include "relrc.h"

relrc.h: declare a function in th header:
void get_emis_disk_corona(relParam* param, double* emis, double* re, int n_r, int* status);

reltable.h: declare a function in th header:
void init_rc_table(char* filename, rcTable** inp_tab, int* status);

reltable.c: change from
lpDat* load_single_lp_nk_Dat(fitsfile* fptr, int n_h, int n_rad, int i, int j, int rownum, double defpar[], int nhdu, int* status)
to
lpDat* load_single_lp_nk_Dat(fitsfile* fptr, int n_h, int n_rad, int i, int j, int rownum, float defpar[], int nhdu, int* status)

[danehkar]

fix the issues with old FITS files for a22 (Trf_Johannsen_a22.fits) and e3 (Trf_Johannsen_e3.fits). RELNKTABLE_NG is 40 in Trf_Johannsen_a13.fits, but it is 20 in Trf_Johannsen_a22.fits and Trf_Johannsen_e3.fits.

reltable.c: add:
extern int rel_nk_table_ng;

relbase.h: add:
#define RELNKTABLE_NG_OLD 20

relbase.c: add:

char* get_filename(int * status){
int mdot_type = current_mdot_type;
int def_par_type = current_def_par_type;
// printf("%d %d\n", def_par_type, mdot_type);
rel_nk_table_ng=RELNKTABLE_NG_OLD;
if (mdot_type == 0) {
if (def_par_type == 1) {
       rel_nk_table_ng=RELNKTABLE_NG;

relatable.c: replaced RELNKTABLE_NG with rel_nk_table_ng