viewcell2b is slow

[torbenott]

viewcell2b is very slow and it seems mainly to be caused by repeated call of uistack(). Replace use of uistack?

[torbenott]

Addressed in 715abed by making call of uistack optional. Speed gain about 2x. Still slow mainly because of plotting lines individually in excessive looping for each spike - a bit more involved to fix that.