python: get_header_names()

[Psy-Fer]

get all header names and dump to user as list.

Then use slow5_hdr_get() to get values

BLOCKER: need C API to access keys in hashmap Something like: slow5_hdr_names(uint32_t read_group, const slow5_hdr_t *header); Return something I can parse into a python list on the other end. @hasindu2008

[Psy-Fer]

Looked at the closed issues, and it looks like @hiruna72 and I think the same. Eposing something like slow5_extract_hdr() will do the trick

[hasindu2008]

Use the following function

//get the list of hdr data keys in sorted order (only the returned pointer must be freed, not the ones inside - subjet to change)
//len is the numberof elements
//returns null if no attributes
const char **slow5_get_hdr_keys(const slow5_hdr_t *header,uint64_t *len);

[Psy-Fer]

Yep this works. Cheers