Behaves similar to string[string] but case does not matter for the key, the insertion order is not changed and multiple values per key are supported.
This kind of map is used for MIME headers (e.g. for HTTP), where the case of the key strings does not matter. Note that the map can contain fields with the same key multiple times if addField is used for insertion. Insertion order is preserved.
Note that despite case not being relevant for matching keyse, iterating over the map will yield the original case of the key that was put in.
alias InetHeaderMap = DictionaryList!(string,false,12L,false);