Major updates

 * Added "nbt_new_<type>()" functions that initialize a valid new tag
 * Changed "nbt_set_<list types>" to take the values directly
   as arguments instead of wrapped in their own types
      TODO: Provde a nicer way to add or remove values at given
            positions
 * Added "nbt_get_length()" to get the length of lists, compounds and
   byte arrays
 * Added "nbt_get_list_type()" to get the type of a list
 * Adapted "nbt_add_tag()" to only add to compounds now and take a
   pointer to an "nbt_tag" instead of creating the tag itself
3 files changed