Added unused stub timestamped_page_ptr_t.
Made current_page_acq_t use timestamped_page_ptr_t.
Made buf_lock_t::get_recency wait for read access.
Made recencies computed upon access, not upon current_page_acq_t construction.
Fixed assertion in timestamped_page_ptr_t to allow deleted (NULL) page representation with invalid timestamp.
A slight refactoring of pulse_pulsables recency values.
Removed the recency_ field from current_page_acq_t.
Added unused manually_touch_recency method.
Made btree split, merge, level, and root insertion operations manually touch the recency.
Found a cleaner way to construct loop.
Fixed new root block manually_touch_recency call to use recency value and not crash.
Removed or renamed some "temp" bufs.
Added write-cond waiting for write acquirers in recency() to make view of recency consistent.
Updated comments in get_recency() and recency() to be more clear.
Merge branch 'sam_2053' into next