Reaction Toolkit Introduction:
New object properties:
Atoms have a "map class" property.
dt_mapclass(atom) => dt_Integer value
dt_setmapclass(atom, value) => dt_Boolean success
Molecules have a "role" in a reaction, which is one of: DX_REACTANT,
dt_getrole(reaction, molecule) => dt_Integer constant
dt_addcomponent(reaction, molecule, role) => dt_Handle mol_copy
Molecules can have a reaction as their parent.