Remove (integrate) the _get_period_stories_date_where_clause() subroutine because it has been used only once
Rename aliases to more descriptive names (because it's hard to spot a difference between "s" and "ss")
Fix indenting in the query
Use generate_cdts_data() helper subroutine for generating dump tables
Generate a "dump_story_bitly_click_counts" table which will contain sums of Bit.ly click counts for each story in the "dump_stories" table (limited by the time slice date period); make _write_story_link_counts_dump() use the newly created dump table