They're no longer just dealing with methods (procs, helper methods, methods on objects), and I feel like :label can be confused with the other :label.
How about :member_* (as in member of the collection)?
Obviously need to allow backwards compatibility for a while.
Doing this now. Also renaming :group_value_method to just :group_value, although I'm thinking about deprecating that bad boy.
Renamed (with backwards compatibility) and deprecation notices) :labe…
…l_method => :member_label, :value_method => :member_value and :grouped_label_method => :grouped_label. Fixes #533.