Export current element to SNIRF (#118)

* Bug in StimEditGUI in no stim conditions

* Removed export to script, add export to SNIRF option in File menu

* added *.asv to gitignore

* GetAllData method for proc result class returns non-empty DataClass properties

* GetAllData returns misc contents

* Don't call save on nonexistant Snirf subobjects

* Remove 'SnirfDraft = '3'' from mdt defaults

* ;

* Add GetProbe interface. TODO add warnings. Remove faulty setter.

* ExportSnirfGUI

* Update ExportSnirfGUI.m

* Avoid crash on empty misc