Implement a RawConstitutiveLaw
Make WFAssemblier implementations depend on ConstitutiveLaw

  - also add interface SupportLagrange
  - LagrangeWFAssemblier implements SupportLagrange
add Linear2D ShapeFuncion and LinearLagrangeDirichletProcessor
Release a err limit for a MLSTest

  - trivial
In Polygon2D, and refresh() and let polygon refresh after fractionize()

  - also add an argument check in fractionize, which prevents endless loop
Add interface GenericFunction
Add functions to TimoshenkoAnalyticalBeam2D

  - also correct constructor
  - add inner classes that implement GenericFunction
    + volumn force
    + Neumann boundary condition
    + dirichlet boundary condition
  - make accordingly constitutiveLaw() generator
Make GaussLegendre as basis tools for quadrature
Add Segment2DQuadrature tool and test
Make QuadrangleQuadrature tool and test it
add InfluenceRadsCalc interface and implement the Constant* edition