Add possibility to set default values for new rules

If for some reason you need to create many login destination rules, there is currently no way to set defaults for new rules. Many rules are needed e.g. if there are multiple registration questionnaires per role. Also currently the new rule always is inserted by default below old rules when the rules have the same weight. Because the delta for the weight selection is always the default 10, after 20 rules it might not be possible to get a new rule on top of the list - at least without changing the weight of some other rule(s).

The attached patch adds the possibility to set many default values for new rules, such as destinations and pages, in the Settings tab. There is also a default weight selection, which makes it possible to make new rules to always come to the top (or bottom) of the list.

Hope this is of some use to someone.