Create journal for graph when opened
Create journal for graph when opened

Gives ability to undo/redo for all graph changes during a session.
No persistence for now.

lxfschr/noflo-ui,noflo/noflo-ui,noflo/noflo-ui,lxfschr/noflo-ui,rasata/noflo-ui,flyboarder/noflo-ui,rdf-pipeline/noflo-server,oportocala/noflo-ui,taylorzane/noflo-ui,rdf-pipeline/noflo-server,rasata/noflo-ui,oportocala/noflo-ui,taylorzane/noflo-ui