Gets the configuration object or section associated with a particular
package or module.
Parameters :
packageormod : str or None
The package for which to retrieve the configuration object. If a
string, it must be a valid package name, or if None, the package from
which this function is called will be used.
Returns :
cfgobj : configobj.ConfigObj or configobj.Section
If the requested package is a base package, this will be the
configobj.ConfigObj for that package, or if it is a subpackage or
module, it will return the relevant configobj.Section object.
Raises :
RuntimeError :
If package is None, but the package this item is created from cannot
be determined.