Made page_cache_t not be a friend of page_t.
Removed is_not_loaded function.
In eviction_bag_t, removed add_without_size and add_size, added change_size.
Added and made use of evicter_t::adjust_usage.
Removed some unhelpful RSI comments.
Removed compute_in_memory_size.
Removed some more unhelpful RSI comments.
Made to_standard_block_token take argument by value.
Removed useless RSI comment.
Removed the field page_t::max_ser_block_size_.
Removed a useless RSI about removing get_data_read().
Removed RSI in page.cc about checking serbuf_ and block_token_ assigners.
Made region_tree_filler_t call get_data_read() for its assertion.
Checked unchanged hypothetical_memory_usage unchanged in init_block_token.
Added usage_adjuster_t to get the proper memory-usage adjustments in the cache when a block is resized.