Fix/ionex padded 16i5 lines

[yhw605]

Summary

ESA GIM IONEX products (e.g. ESA0OPSFIN_20240010000_01D_02H_GIM.INX) use 73 longitudes (-180 to 180, step 5). Each latitude band is Fortran 16I5, so the last record has 9 values plus 35 trailing spaces to pad the line to 80 columns.

Part of ESA GIM TEC MAP is listed below:

     4                                                      START OF TEC MAP    
  2024     1     1     6     0     0                        EPOCH OF CURRENT MAP
    87.5-180.0 180.0   5.0 450.0                            LAT/LON1/LON2/DLON/H
   52   52   52   52   52   52   53   53   53   54   54   55   55   56   56   57
   57   58   58   59   59   59   60   60   60   60   61   61   61   61   61   61
   61   61   61   61   61   61   61   61   61   60   60   60   60   60   60   60
   60   59   59   59   59   59   58   58   58   57   57   57   56   56   56   55
   55   54   54   53   53   53   52   52   52                                   

and there are 35 blank space at the tail of a specified latitude of TEC Map.

This strips per-line padding, accepts CRLF, and adds truncated unit tests. The full ESA product file is not included.