Used segmented_vector_t in free_list_t.
Removed RSP about backindex_bag_t having segmented_vector_t.
Made live_acqs_ merely be a size_t.
Addressed some RSP concerns (that were not big concerns) about the preceders_ and subseqers_ arrays, among other things.
Made us yield a bit when destructing current_pages_ pointees.
Made segmented_vector_t be a spare data structure.
Turned some RSPs into KSIs.
Merge branch 'sam_multiple_iii_better' into sam_rsp
Merge branch 'sam_multiple_iii_better' into sam_rsp
Merge branch 'next' into sam_rsp
Merge branch 'sam_rsp' into next