The steps used in reading a grib file

seek_grib2 -- finds next grib message

int read_grib2(FILE *file, long pos, long len_grib, unsigned char *buffer);
	reads a grib2 message and saves in buffer

int parse_1st_msg(unsigned char **sec); reads buffer and returns sec
int parse_next_msg(unsigned char **sec); reads buffer and returns sec

wgrib2.h:int unpk_grib(unsigned char **sec, float *data);

possible program interfaces for reading

	1)	read N.M/byte_location
