refextract: add recid support to extraction-jobs

• Adds the ability for record ids to be specified inside extraction-job files. Fulltext files associated with these recids will be used in the extraction process.

• Shift extraction-job parsing into _task_submit_elaborate_specific_parameter, from _task_run_core.

• Renames collection and recid task options to 'collections' and 'recids'. This coinsides with bibclassify's notation.