remove levels from trial type column

Author: Remi-Gau

src/saveEventsFile.m

@@ -182,15 +182,11 @@
     % before calling openFile.
 
     % initialize holy trinity (onset, trial_type, duration) columns
-    logFile(1).columns = struct('onset', struct( ...
-                                                'Description', ...
+    logFile(1).columns = struct('onset', struct('Description', ...
                                                 'time elapsed since experiment start', ...
                                                 'Units', 's'), ...
-                                'trial_type', struct( ...
-                                                     'Description', 'types of trial', ...
-                                                     'Levels', struct()), ...
-                                'duration', struct( ...
-                                                   'Description', ...
+                                'trial_type', struct('Description', 'types of trial'), ...
+                                'duration', struct('Description', ...
                                                    'duration of the event or the block', ...
                                                    'Units', 's') ...
                                );