Add List class to new lib/utility.rb in anticipation of simplifying all of the extant *List classes.
Refactor JobList to subclass List, reducing duplication.
Add List#each in anticipation of refactoring *Lists that use it.
Refactor JobApplicationList to subclass List, reducing duplication.
Rename instance variables in List to @list_items. Some domain-specific names from other classes had slipped in.
Refactor JobApplicationRecordList to subclass List, reducing duplication.
Refactor SavedRecordList to subclass List, reducing duplication.
Refactor PostingList to subclass List, reducing duplication.
Add List#select in anticipation of refactoring away #items_filtered_for, as its first parameter is redundant.
Replace each usage of List#items_filtered_for with the more consistent #select.
Remove unused List#items_filtered_for.
Make List#add private, preferring that children of List use more domain-specific verbs.

Make JobList#add and JobApplicationList#add public, but only until the discovery of a more domain-specific verb.