update to meet @tridelat's points
update to meet @tridelat's points

Dimension is no longer given a default argument in initialization (this might require a fix to the test suite, which I'll put in a separate commit if it comes up).  Regions are no assigned on the middle of the x- wall of the tank, rather than the center of the tank (as Tristan brought up that the center is often occupied by other shapes).
erdc/proteus,erdc/proteus,erdc/proteus,erdc/proteus