added section on fuel cycles. for each section, I also added a metadata member
and described it in the intro. I also added a small statement about the GND
paper. readme has been spell checked.
added basic framework for fuel cycle translator and corresponding testing framework
control block (sim info) content added, passes tests

testing function signature take a single object per type of test, default
objects included.
added ability to translate initial conditions and tests.

updated the default arguments for simulations to a private function like the
default class maps

separated out the tests from the tools that help set them up. things are much
clearer now, and a straightforward workflow has been established
updated test signatures to include growth

testing now correctly outputs the xml and json representations of the growth
section
added a notion of production connections (ie which facilities produce what commodities)
changed translation functions and tests to only return xml trees. added a helper
function to test equivalence of xml trees. fuel cycle work complete.
fuel cycle translation now complete with tests.