Allow custom talents to have multiple modifiers

[dvbuntu]

Custom talents should support multiple modifiers. For example, a talent should be able to add a skill as a career skill and also give a free rank (or other modifier) in that skill. Currently, custom talents can have just one type of modifier (though they can add multiple skills as career).

[KoljaTM]

This is not currently something that "builtin" talents seem to have (I think?). Does it make sense to add this functionality for custom talents?