break out persistent obligation handling
break out persistent obligation handling

The logic for saving and loading contract obligations was more
complicated than the logic for handling the rest of the persistence, so
it was broken out into a separate function for each loading and saving

mnsl/Sia,rivine/rivine,ericflo/Sia,mharkus/Sia,mtlynch/Sia,ChrisSchinnerl/Sia,ericflo/Sia,NebulousLabs/Sia,mtlynch/Sia,Mingling94/Sia,ChrisSchinnerl/Sia,mharkus/Sia,MrStrong/Sia,MrStrong/Sia,rivine/rivine,mnsl/Sia,NebulousLabs/Sia,johnathanhowell/Sia