Add a  if more than 40 rows are returned. Related to #1307
Replace >> with an arrow -- Related to #1307
Trying a infobox instead of just a link for  -- Related to #1307
Implemented a rudimentary (slow) serialize_onto_blob implementation.
Added inefficiently implemented deserialize_from_blob function.
Merge branch 'next' into sam_1431
Made internal_disk_backed_queue_t use write_onto_blob but not any sort of blob deserialization.
Merge branch 'next' into sam_1431
Made write_stream_t::write use MUST_USE.
Added buffer_group_write_stream_t type.
Removed unnecessary vector and string copying in serialize_onto_blob and deserialize_from_blob (but there still is unnecessary write_message_t copying).
Moved write_onto_blob implementation to serialize_onto_blob.cc.
Fixed comment refering to a vector_stream_t that happens to now be a string_stream_t.
Made kv_location_set use serialize_onto_blob.
Removed a ridiculous comment.
Made get_secondary_indexes_internal use deserialize_from_blob.
Made disk_backed_queue avoid copying when reading.
Adds the starts of the explain code.
Adds a unittest for explain.
Pushes through tasks. They're now in the env_t.