v1.16.6

-- Remove output format as a user option to export data.  Per David's argument against exporting to Excel on basecamp: "I am nervous about excel exporting… this will always break for us because of Microsoft and matlab always changing. And we can’t test all of the scenarios. ... I feel that we should not support that sort of exporting. " -- Mar 17, 2020.
-- Changes to exporting code to avoid generating error when there's no HRF. It should instead either generate empty file or not generate a file at all and display a message box saying there's no HRF
-- Reposition/resize some ExportDataGUI.fig objects
-- Update README file to more wiki-friendly text