Document DERSL
Fix error in processStudentName if name doesn't have a ` character
DERSL: Don't process elements of tiedHonorees if tiedSchools is null

If we're using three columns, we can assume that the elements of
tiedHonorees represent schools, which should not receive name
processing.
DERSL: Check structure of honorees and schools when adding a list
DERSL addTie methods: Handle null entries in tiedSchools

This could represent an independent competitor who does not have a
school, so we want to allow it to be processed properly.
Clarify the documentation of ArrayUtils.multiSort