make tick/tocking deterministic
lexigraphical compare on req/bid pointers
added a number of default value constructors to exchange node, and added an id on which it can be sorted, i.e., the agent id
sort->stable_sort for all greedy sorting
updated pref compare to look at equality then node ids
fixed avg pref compare
Merge branch 'det' into develop
added vect dbl support to sqlite backend
Merge branch 'rwcarlsen-vdbl' into develop