structure finished for reactor/supplier init
implementation fleshed out, needs testing
added preference functions
updated instance generation to use commodities based on fidelity and rxtr kind
updated suppliers for fidelity and added fidelity tests for n rxtrs and n suppliers
gen_inst inital tests pass!
fixed bug in data conversion
fully tested nodes, groups, arcs in each fuel cycle
clarified tests a bit
preference and region functions made independent of points and tested