regidx_init() - creates new index
@param fname: input file name or NULL if regions will be added one-by-one via regidx_insert()
@param parsef: regidx_parse_bed, regidx_parse_tab or see description of regidx_parse_f. If NULL,
the format will be autodected, currently either regidx_parse_tab (the default) or
regidx_parse_bed (file must be named 'bed' or 'bed.gz') will be used. Note that
the exact autodetection algorithm will change.
@param freef: NULL or see description of regidx_parse_f
@param payload_size: 0 with regidx_parse_bed, regidx_parse_tab or see regidx_parse_f
@param usr: optional user data passed to regidx_parse_f
regidx_init() - creates new index @param fname: input file name or NULL if regions will be added one-by-one via regidx_insert() @param parsef: regidx_parse_bed, regidx_parse_tab or see description of regidx_parse_f. If NULL, the format will be autodected, currently either regidx_parse_tab (the default) or regidx_parse_bed (file must be named 'bed' or 'bed.gz') will be used. Note that the exact autodetection algorithm will change. @param freef: NULL or see description of regidx_parse_f @param payload_size: 0 with regidx_parse_bed, regidx_parse_tab or see regidx_parse_f @param usr: optional user data passed to regidx_parse_f
Returns index on success or NULL on error.