the greedy solver now orders which nodes it will satisfy by average preference
added a test
moved greedy solver related test into new file
removed vestiges from preconditioner tests
changed vectors to sets to prevent duplicates in commod recipe ctx
added a small bit of clarifying documentation
a bit more docs
fixed cycpp codegen error for set.insert
fixed iteration-erase bug in ApplyThreshold
Merge branch 'fix-crctx-again' of https://github.com/rwcarlsen/cyclus into rwcarlsen-fix-crctx-again
Merge branch 'node-order' of https://github.com/gidden/cyclus into gidden-node-order
documentation clarification on exclusive node groups
added test for recently fixed crctx bug of duplicate commods
test for incorrect map iteration bug in ApplyThreshold
Merge pull request #814 from rwcarlsen/bugs-fix

add tests for bugs fixed in #811