Add FemElement2DTriangle. Missing stiffness and mass matrix calculation and test
Add Unit Test for FemElement2DTri isValidCoordinate/computeCartesianCoordinate
Makes MultiAxisDevice a CommonDevice so filters can get its input data.

Adds a CommonDevice constructor that takes just the name...good for
serialization, and that way the input DataGroup will be able to be
assigned to any DataGroup on the first call to initializeInput.
Cleans up MultiAxisDevice header file.
Adds documentation.
Moves implementations to cpp file.
Adds PoseTransform device filter.
Add Fem2DElement mass/stiffness matrix + complete unit tests

+ cpplint compliant
+ doxygen compliant
+ Debian32 compliant
Adds unit tests for PoseTransform device filter.
Initialize PoseTransform in unit tests.
Cleanup cmake include_directories for DeviceFilters.
Add LinearSpring viscosity term (force vector, stiffness and damping matrices)

Adjust the Massspring example to use this new parameter
Add new unit test to verify the force derivatives (stiffness and damping matrices), using a numerical derivation.
PoseTransform filters the output data sent to haptic devices.
Does not yet filter all the data.
Clean up FemElem2D::computeShapeFunctionsParameter

Clean bad loops and unnecessary temporary variable double x[3], y[3].
Reduced evaluation to non-null parts only, take into account that x0=y0=y1=0
Clean transformation from global 3D to triangle 2D local coordinates

Use the RigidTransform3d to apply the transformation inverse.
Much cleaner than accessing the m_R0 3x3 block all the time, and doing the rigid transformation by hand (removing the translation part and apply the rotation).
Renaming methods to follow coding standard in FemElem2D
Fix incorrect handling of boundary conditions in PlyReader
FemElem2D test against epsilon + typo + compare double variable against 0.0
Store membrane shape functions (3 x 3param) in a 3x3 matrix
Finishes the filter functions for PoseTransform.
FemElem2D: rename m_R0 in m_initialRotation + make it a 3x3 matrix (not 18x18)
FemElem2D: clean up member variables that can be locally defined

    Matrix36Type m_membraneStrainDisplacement; //< Strain-displacement matrix containing (dfi/dx=bi , dfi/dy=ci)
    Matrix33Type m_membraneEm; //< Membrane elasticity material matrix
    Matrix66Type m_membraneKLocal; //< Membrane local stiffness matrix

    std::array<Matrix39Type, 3> m_plateStrainDisplacementAtGaussPoints; //< Strain-displacement at given Gauss points
    Matrix33Type m_plateEm; //< Membrane elasticity material matrix
    Matrix99Type m_plateKLocal; //< Membrane local stiffness matrix