Save As a subset of Trials

[Elizabeth Brainerd]

Rather than deleting many trials from an XMA file in order to send just one or a few trials to someone else, make it possible to Save As and then select which Trial(s) to include in the new file. Would be most powerful to be able to select more than one, but just one would be the most useful option (in case it is hard to allow multi-select and save)

[Benjamin Knorlein]

fixes #43 : Dataset can be saved with only a subset of the trials "Save subdataset as"

→ <<cset 8a22279ac9b8>>