Remove Silence Finder plug-in

as discussed between QA and RM.

src/commands/ScreenshotCommand.cpp

@@ -531,7 +531,6 @@ void ScreenshotCommand::CaptureEffects(
       "Label Sounds...",
       "Regular Interval Labels...",
       "Sample Data Export...",
-      "Silence Finder...",
 #endif
    } );
 }

src/effects/nyquist/LoadNyquist.cpp

@@ -42,7 +42,6 @@ const static wxChar *kShippedEffects[] =
    wxT("rissetdrum.ny"),
    wxT("sample-data-export.ny"),
    wxT("sample-data-import.ny"),
-   wxT("SilenceMarker.ny"),
    wxT("spectral-delete.ny"),
    wxT("SpectralEditMulti.ny"),
    wxT("SpectralEditParametricEQ.ny"),