BUG: change ParaView_MAJOR to only contain version information without

leading text

* Something like ParaView_MAJOR=ParaView_3.6 would have previously
  been possible, but this violates paraview's expectation of having
  "lib/paraview-<digits>.<digits>"

* TODO? If desired, the ParaView_MAJOR could be determined
  automatically in the script.

  For example,
      ParaView_MAJOR=`echo $ParaView_VERSION | \
          sed -e 's/^\([0-9][0-9]*\.[0-9][0-9]*\).*$/\1/'`

  Or even,
      ParaView_MAJOR=${ParaView_VERSION%.[0-9]}

  Except that the second version fails if the minor version reaches
  double digits.