Make OptionalValue comparable
Use typedef in MeshElement
Add MeshRepresentation and OsgMeshRepresentation

also add class to generate normals on demand
Add unit test for mesh
cpplint fixes
Refactor mesh construction and updates to produce functions and use member variables
Add rigid transform creation utility function
Remove Lighting from UnitAxes

This will make the unit axes unlit in all cases
Fix Updating un the OsgMeshRepresentation

tell osg that nodes are being updated
Refactor test to dynamically move the mesh vertices

Discared behavior in favor of direct manipulation of the vetices, discarded static test ...
Refactor cube creation
cpplint and documentation fixes
fix linux build warning

I don't really know what is wrong with the assignment, there seems to be a bug with gcc but it looks like it not really related to this expression
[Incomplete] Added Vector Field Representation
[Incomplete] Give a Vertices (data structure) of vertices, OsgVectorRepresentation can visualize line segments now. But colors of each vector hasn't been implemented yet
Added a point to indicate the origin of the coordinate
Revised how vectors are drawn, associated colors with each vector
Finished implementation of Vector Field Representation. Vector(s) is added as extra data of each point, color is added as extra information of each vector. Revised unit tests and render tests.
Construct a struct of vector and color as Data information to a Surgsim::DataStructures::Vertex
Move SurgSim::DataStructures::Vector to SurgSim::Graphics::VectorFiled, update classes, tests accordingly.
Vary vectors and locations where to draw vectors (separately) in render test