Graph: Added back DefaultEdgeRoutingAlgorithm/DefaultOverlapRemovalAlgorithm. (Bug/...)

- OverlapRemovalAlgorithm seems to have no effect when loading a file.
YodiiLayout: Place new plugins/services under their parents, if applicable.
IDiscoveredInfo.IsValid(): Fixed silly order bug.
Consolidated icons in /Assets/Icons/.
Added icons+License for New/Open/Save buttons.