Document & modify all shape funs

[yangbai90]

All the shape fun classes should offer the illustration of the node ordering, and make them consistent with the VTK cell. All the sub shape fun classes should use the same node ordering as the VTK cell.

Checklist:

• Edges in 1D
• Quad4 in 2D case
• Quad8 in 2D case
• Quad9 in 2D case
• Tri3 in 2D case
• Tri6 in 2D case
• Hex8 in 3D case
• Hex20 in 3D case
• Hex27 in 3D case
• Tet4 in 3D case
• Tet10 in 3D case

[yangbai90]

Resolved in a978190