Comment 1 for bug 284614

Python's ConfParser class is implemented so that
- When an option has multiple form, the first encountered long name is the one to use in the conf file.
- When an option contains - in its name, the - should be tranformed in a _ in the conf file.
- When the destination variable name is specified, it is the variable name that should be user.

=> Added hints in help for ambiguous values.