Move struct and exports into .h file so they can be used elsewhere. Also prevent toString from crashing if the atom is nil.
Move struct and exports into .h file so they can be used elsewhere.
Also prevent toString from crashing if the atom is nil.

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb