Various Ergonomic Improvements

DataStub is now indexable

• Instead of using DataStub.load(...) DataStubs now utilizes natural MATLAB indexing behavior: DataStub(...).
• DataStub.load() behavior is retained for backwards compatibility.
• DataStubs are now Sealed which means they cannot be subclassed.

DynamicTable objects

• new getRow() and addRow functions which allows for adding to a dynamic table by row.
• For more information, take a look at the convertTrials tutorial.

Miscellaneous

• Various bugfixes for DataStub bugs
• Basic Usage and Trial Conversion tutorials updated to use DynamicTable and DataStub methods.