Introducing a TimeSeries.convolve() method based on the overlap-save algorithm
Created by: alurban
@duncanmmacleod, this PR introduces a TimeSeries.convolve()
method which efficiently applies an FIR filter to a long timeseries using the overlap-save algorithm. It also adds a unit test for TimeSeries.convolve()
which prepares a timeseries and then checks that the input data are unchanged by convolving with a delta function.
@andrew-lundgren, this fixes #451 (closed).