[Kst] [Kst-plot/kst] 33d5d6: Better padding for high pass and band pass filters

[Barth Netterfield]

  Branch: refs/heads/master
  Home:   https://github.com/Kst-plot/kst
  Commit: 33d5d678c462145f62370f4a5501c4c8a8aa756a
      https://github.com/Kst-plot/kst/commit/33d5d678c462145f62370f4a5501c4c8a8aa756a
  Author: Barth Netterfield <netterfield at astro.utoronto.ca>
  Date:   2014-06-13 (Fri, 13 Jun 2014)

  Changed paths:
    M src/kst/main.cpp
    M src/plugins/filters/butterworth_bandpass/butterworth_bandpass.cpp
    M src/plugins/filters/butterworth_bandstop/butterworth_bandstop.cpp
    M src/plugins/filters/butterworth_highpass/butterworth_highpass.cpp
    M src/plugins/filters/butterworth_lowpass/butterworth_lowpass.cpp
    M src/plugins/filters/filters.h

  Log Message:
  -----------
  Better padding for high pass and band pass filters

Pad with an extraopolated polynomial before high pass
filtering.  This greatly reduces ringing edge effects in
most cases.