refactor path location a bit to be more useful to loki. make graphreader easier to use if you already have a pt and dont need the hierarchy.  update graphtile to use size_t in place of int and to use c++ style casts instead of c style casts, also to use array operators instead of pointer arithmetic as its more obvious
Merge remote-tracking branch 'origin/master' into kk_loki
Merge pull request #14 from valhalla/kk_loki

updates to pathlocation and graphtile for loki
Merge branch 'master' of https://github.com/valhalla/baldr into gdg