headerParseParamList
Parses a header which is a comma-delimited list of something like: token [ "=" ( token | quoted-string ) ]
.
Tokens that don't have an associated value will still be added to the resulting hash table, but with a null value.
This also handles RFC5987 encoding (which in HTTP is mostly used for giving UTF8-encoded filenames in the Content-Disposition header).
Return
a #GHashTable of list elements, which can be freed with func@header_free_param_list.
Parameters
header
a header value