graph: add Moving Target D* Lite and Field D*
Created by: kortschak
MT D* Lite: http://idm-lab.org/bib/abstracts/papers/aamas10a.pdf Field D*: http://robots.stanford.edu/isrr-papers/final/final-23.pdf
I have a D* Lite implementation done, but am waiting on #85 to submit that - and will then make the necessary fork/mods for MT D* and Field D*.