Split query in optimal sub-queries
pxweb_split_query(pxq, px, pxmd)a list with pxweb_query objects.
a pxweb_query object.
a pxweb object.
a pxweb_metadata object.
Computes (brute-force) the optimal split of a query to match the api maximum value limit. It also take into account that time variables and content variables should not be split. Also variables with filter "top" should not be split, since the top filter does not supply the individual levels, just a number. This can probably be improved further.