change plot activity marks from magenta to white; restore 2-level movie handling
change plot activity marks from magenta to white; restore 2-level movie handling

In a movie with only two illumination levels, assume it is CS-only
unless FISHSPY_TRIAL_COUNTS specifies the duration of test phases.

informatics-isi-edu/fishspy,informatics-isi-edu/fishspy,informatics-isi-edu/fishspy,informatics-isi-edu/fishspy