Fix an issue in LOCALE_IO class, used to switch to/back locale "C" when reading/writing files: the back to locale was broken, and created issues in countries using the ',' as fp separator, especially when the non default language was used.

It was reported in many bugs.

eeschema/plot_schematic_PS.cpp

@@ -151,7 +151,8 @@ bool DIALOG_PLOT_SCHEMATIC::plotOneSheetPS( const wxString&     aFileName,
         return false;
     }
 
-    SetLocaleTo_C_standard();
+    LOCALE_IO toggle;       // Switch the locale to standard C
+
     plotter->StartPlot();
 
     if( aPlotFrameRef )
@@ -168,7 +169,6 @@ bool DIALOG_PLOT_SCHEMATIC::plotOneSheetPS( const wxString&     aFileName,
 
     plotter->EndPlot();
     delete plotter;
-    SetLocaleTo_Default();
 
     return true;
 }