I/O test fixtures for normal boluses
cherry-pick me! make sure all basal events get completely built, incl. common fields
cherry-pick me too! small bugfix for settings history
fill out remainder of I/O test fixtures for boluses, old and modern pumps
fix bugs exposed during test-writing and fill in logic for older model pumps
update test driver to run I/O test on old vs. modern pumps for boluses