Reset analyserZoomX/Y state for new opened logs (#717)

resolved issue #694: Reset analyserZoomX/Y state for new opened logs

Author: demvlad

js/graph_spectrum_plot.js

@@ -54,6 +54,8 @@ GraphSpectrumPlot.initialize = function(canvas, sysConfig) {
     this._invalidateCache();
     this._invalidateDataCache();
     this._logRateWarning = undefined;
+    this._zoomX =  1;
+    this._zoomY =  1;
 };
 
 GraphSpectrumPlot.setZoom = function(zoomX, zoomY) {