Create a postprocessor for complete material output.

This is a proposed postprocessor for the complete output of the evaluate function of the material model. We are currently working with a material model that is very slow / complicated and I was annoyed by the waste of time to call the evaluate function for every material property output, although they are all evaluated in the same function. There would be other ways to achieve this, but they would all include larger changes in the material model interface (e.g telling the evaluate function what property is asked for) and we would always have the overhead of setting up an material_model_inputs and _outputs for just one returned quantity. Let me know what you think about it, and I could adjust it.
I find the logic with the 'i+k' slightly difficult to follow. how about doing something like this:

unsigned int output_index = 0;
for (i=0; i<...; ++i, ++output_index)
  if (...)
    computed_quantities[q][output_index] = ...;

This way one doesn't have to think about possible values of i and k, but instead just use output_index everywhere.