Work in progress implementing a serialization_sort pipeline node. (#57)
wip
graph.cpp: Fix is_depending reporting incorrectly for evacuation.
Fix test/sort plotting to stdout instead of stderr.
Move predwrap out of merger.
serialization_sort.h: Move phase 2 fanout check into calculate_parameters.
Add ut-pipelining_serialization sort test.
Introduce serialization_bits::merger.
In serialization merge sorter, save the last merge level for the outputting phase.