Output rank two tensor components and scalars (i.e. vonmises) on a user specified line
------------------
- `LineMaterialRankTwoSampler` [Doxygen](http://mooseframework.org/docs/doxygen/modules/classLineMaterialRankTwoSampler.html) 
- `LineMaterialRankTwoScalarSampler` [Doxygen](http://mooseframework.org/docs/doxygen/modules/classLineMaterialRankTwoScalarSampler.html)


To output the components or scalar quantities of rank two tensors, i.e. stress and strain tensors, on a user specified line, the material objects must first be declared as auxiliary variables and use appropriate vector postprocessors. LineMaterialRankTwoSampler is used to sample a RankTwoTensor component, and LineMaterialRankFourScalarSampler is used to sample a RankTwoTensor scalar.  For example, $$\sigma_{xx}$$, and $$\sigma_{vonmises}$$ can be sampled by first declaring auxiliary variables for them in the input file:

```puppet
    [AuxVariables]
      [./stress_xx]
        order = CONSTANT
        family = MONOMIAL
      [../]

      [./vonmises]
        order = CONSTANT
        family = MONOMIAL
      [../]
    []
```
 
Next, the appropriate vector post processors are used.  They require the start point and end point of the line on which you want to sample the value, the name of the material property that you wish to see the field value for, the indices of the tensor value (either 0, 1, or 2) or the type of the scalar, and the way how you want to sort your output value.  For example, 

```puppet
    [VectorPostprocessors]
      [./sample_stress_xx]
        type = LineMaterialRankTwoSampler    # vector postprocessor type
        start = '0 0 0'                      # starting point of a line
        end = '1 1 1'                        # end point of the line
        property = stress                    # name of the material property
        index_i = 0                          # the first index i, from 0 to 2
        index_j = 0                          # the second index j, from 0 to 2
        sort_by = id                         # the sort_by sequence how you want to output the results
      [../]

      [./sample_vonmises]
        type = LineMaterialRankTwoScalarSampler
        start = '0 0 0'
        end = '1 1 1'
        property = stress
        scalar_type = VonMisesStress         # type of the rank two tensor scalar 
        #possible options: VonMisesStress EquivalentPlasticStrain Hydrostatic L2norm MaxPrincipal MidPrincipal MinPrincipal VolumetricStrain FirstInvariant SecondInvariant ThirdInvariant AxialStress HoopStress RadialStress TriaxialityStress Direction
        sort_by = id
      [../]
    []
```