Fix compil issues, especially on Windows:

Replace SEVERITY_ERROR by RPT_SEVERITY_ERROR to avoid collision with a system definition.
Replace other SEVERITY_XXX by RPT_SEVERITY_XX for consistency.
Fix compil warnings and some other compil issues.

eeschema/dialogs/dialog_plot_schematic.cpp

@@ -331,7 +331,7 @@ wxFileName DIALOG_PLOT_SCHEMATIC::createPlotFileName( wxTextCtrl* aOutputDirecto
     {
         wxString msg = wxString::Format( _( "Could not write plot files to folder \"%s\"." ),
                                          outputDir.GetPath() );
-        aReporter->Report( msg, SEVERITY_ERROR );
+        aReporter->Report( msg, RPT_SEVERITY_ERROR );
     }
 
     wxFileName fn( plotFileName );