Allow exporting multiple tasks

[arnodelorme]

Upon discussing with Dung, the bids_export should handle task export because it is irrelevant to EEGLAB studies. Example below

data(1).file = {fullfile(dataPath, 'sub-001', 'ses-01', 'eeg', 'sub-001_ses-01_task1-meditation_eeg.bdf')
                fullfile(dataPath, 'sub-001', 'ses-02', 'eeg', 'sub-001_ses-02_task1-meditation_eeg.bdf') 
                fullfile(dataPath, 'sub-001', 'ses-01', 'eeg', 'sub-001_ses-01_task2-meditation_eeg.bdf')
                fullfile(dataPath, 'sub-001', 'ses-02', 'eeg', 'sub-001_ses-02_task2-meditation_eeg.bdf') };
data(1).session = [1 2 1 2];
data(1).run     = [1 1 1 1];
data(1).tasks   = { 'task1' 'task1' 'task2' 'task2' };

tInfo fields should also be modified to handle different instructions and task descriptions.

[arnodelorme]

This goes in the _eeg.json file

[cll008]

Is the taskName opt input not working as intended?

%  'taskName'  - [string] name of the task for all datasets. No spaces and
%                special characters are allowed. Default is 'Experiment'
%                if no tasks are detected, '<taskname>' when single task detected,
%                and 'mixed' when multiple tasks detected. Individual file
%                task can be specified using files.task

[dungscout96]

We will follow up on this issue with https://github.com/sccn/bids-matlab-tools/issues/185