Amalgamation

My euphoria on the topic of principal stresses was premature. I was so pleased to find that the eigenvalue method avoided all the EDividebyZero exceptions in certain test files that I didn't notice it raised a number of EAccessViolation exceptions in entirely different files. The solution was to put the two methods, eigenvalues and poly roots, in series, for version 1.3 of Vtkpost. My latest tests indicate that no nodes in the entire test file group escape from this treatment, (excepting files that fail conversion anyway).