configitems: register 'ui.clonebundleprefers' as example for 'configlist' This exercise the default value handling in 'configlist'.

configitems: register 'patch.fuzz' as first example for 'configint' This exercise the default value handling in 'configint'.

configitems: issue a devel warning when overriding default config If the option is registered, there is already a default value available and passing a new one is at best redundant. So we issue a deprecation warning in this case. (note: there will be case were the default value will not be as simple as what is currently possible. We'll upgrade the configitems code to handle them in time.)