modified demo7 to use new convention. Results match old but not *perfectly*, investigating...
hmmm checked that the small difference isn't due to entering the values wrong, likely due to the change in GSParams from previous runs of this demo.  Looks good enough to me so will revert this commit asap...
Revert "hmmm checked that the small difference isn't due to entering the values wrong, likely due to the change in GSParams from previous runs of this demo.  Looks good enough to me so will revert this commit asap..."

This reverts commit 5c5ddc6a002497f180bddb58bd3400ae50be5ba7.