gerbview command line support

gerbview/files.cpp

@@ -143,6 +143,7 @@ int WinEDA_GerberFrame::LoadOneGerberFile( const wxString& FullFileName,
 
     GetScreen()->m_FileName = filename;
 
+    if( path != wxEmptyString )
         wxSetWorkingDirectory( path );
 
     ChangeFileNameExt( filename, g_PenFilenameExt );

gerbview/gerbview.cpp

@@ -70,6 +70,7 @@ bool WinEDA_App::OnInit()
 
             wxString path = wxPathOnly( fileName );
 
+            if( path != wxEmptyString )
                 wxSetWorkingDirectory( path );
 
             Read_Config();

gerbview/readgerb.cpp

@@ -149,7 +149,9 @@ bool WinEDA_GerberFrame::Read_GERBER_File( wxDC*           DC,
 
     gerber_layer->m_FileName = GERBER_FullFileName;
 
-    wxSetWorkingDirectory( wxPathOnly( GERBER_FullFileName ) );
+    wxString path = wxPathOnly( GERBER_FullFileName );
+    if( path != wxEmptyString )
+        wxSetWorkingDirectory( path );
 
     wxBusyCursor show_wait;
     setlocale( LC_NUMERIC, "C" );