Added option of using previous steps strain rate to soften materials, updated only at the end of the previous step

Moved material transition code to a separate subroutine and tweaked it to check again for transitions after chaning the material number

Added option of defining a dominant material type that will define the element material properties if any volume is present within an element

Replaced ztrans functionality for material transitions below a given depth to a more general transition behavior which allows transitions in at any constant x, y or z value

Added option to assign material properties using a majority or minority rule, to complement what is done with DivFEM