Renamed non-blocking version of serializer_t::block_read to block_read_, proving that nobody externally uses it.
Made non-blocking block_read_ not be part of the serializer_t interface.
Split a line of code with a newline.
Added data_block_manager_t::co_read.
Removed serializer_t::block_read_, making use of data_block_manager_t::co_read.
Removed data_block_manager_t::read, just have co_read.
Renamed data_block_manager_t::co_read to read.