Add experimental instance macro to graph
Add comp-partial test
Add 2-arg version of instance
Fix bug where optional keys were not considered in node ordering.
Add output-metadata to PFnk and update service docs
Revert output metadata change
graph constructor allows merging in inline graphs
lazymap is lazy about error checking
better error messages for graph
Merge branch 'master' of github.com:Prismatic/plumbing_internal
minor cleanup