Parameters in stimulus configuration GUI affect all stimulus locations

[raacampbell]

The stimulus configuration gui allows the user to define where stimuli will presented. It also allows setting of laser power, laser frequency, and rampdown. These latter settings are the same for all stimuli. The GUI has no way to define different powers for different locations. This can, however, be achieved by editing the plain text YAML file generated by the GUI. In the future, the GUI should support this to avoid the requirement to edit the YAML file.