- Correctly ignore parent_portal_type condition when all possible
  portal types are listed.
  This typically saves one stock-catalog join.
- Expand node_category_uid into lists of node_uids.
  This saves one very costly stock-catalog join, as nodes member of given
  category should typically be the minority, inciting MySQL query optimiser
  to use the index materialising this join, preventing use of actual stock
  indexes.
  As there should be few nodes involved in accounting reports, listing
  them all and passing them to queries should not matter much.

Also, add support for src__ parameter.
Also, assorted coding style improvements, changes and code factorisation.