`StdVectorDouble` (and other similar classes) in MATLAB store java objects

[carmichaelong]

This can become an issue downstream. For instance:

table = TimeSeriesTable('filename.mot');
t0 = table.getIndependentColumn().get(0);

t0 is of type java.lang.Double. This then does not work for use with a function such as TimeSeriesTable::appendRow() as the first argument is of type double.

One work around is to pass in t0.doubleValue() instead, but this is difficult to track down for MATLAB users.