WIP on more animation and better routing:
- Modified directed graph code for cleaner separation; each SCMAP.Dijkstra
  object now has its own private data with the graph and results so there
  can be multiple active at the same time
- Added chained tweening to animate the selector from system to system
  along a valid basic route, still needs some bugs fleshed out though
- A little bit of further code cleanup and refactoring