Grebview: add info in layer manager for Excellon drill filles, similar to X2 file function info in X2 gerber files.

common/hotkeys_basic.cpp

@@ -548,6 +548,9 @@ int EDA_BASE_FRAME::ReadHotkeyConfigFile( const wxString&           aFilename,
 {
     wxFile cfgfile( aFilename );
 
+    if( !cfgfile.IsOpened() )       // There is a problem to open file
+        return 0;
+
     // get length
     cfgfile.SeekEnd();
     wxFileOffset size = cfgfile.Tell();