Fix accelarators/mnemonics in dialogs containing radio or check buttons.

Fix accelarators/mnemonics in dialogs containing radio or check buttons.

The GTK+ v2 documentation says accelarators should only be used with
menus. For text entries or buttons, we must use mnemonics.

Replace dlg_check_button_new_with_label_with_mnemonic() and
dlg_radio_button_new_with_label_with_mnemonic() with
gtk_check_button_new_with_mnemonic() and
gtk_radio_button_new_with_mnemonic()

For radio buttons, gtk_radio_button_group is deprecated. Use
gtk_radio_button_new_with_mnemonic_from_widget() to create a new button
in an existing group.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@6165 f5534014-38df-0310-8fa8-9805f1628bb7