Repeated warning text removed.

They will be visibly emitted as warnings anyway.
Removed decimation right before interpolation.

I believe it is not necessary and has no effect at all.
Please correct if I am mistaken.
Reworked the preprocessing.

The steps taken are now:
1. Detrend and taper
2. Decimate
3. Instrument Correction
4. Interpolation
5. Filtering

This should be a reasonable default setting.

The filtering before the decimation is a custom
zerophase Chebychev type 2 filter that has a very sharp
cutoff.