-//HeaderDict *sam_header_merge(int n, const HeaderDict **dicts); // if n=1, the func clones the dictionary
-//char *sam_header_get(const HeaderDict *d, char type[2], int i, char tag[2]);
-//int sam_header_ins(HeaderDict *d, char tp[2], int i, char tg[2], const char *s);
-//int sam_header_del(HeaderDict *d, char type[2], int i, char tag[2]);