Added support to parse keywords to Keyword objects and submissions to Submission objects in Search.new
Added a Container class and Container#method_missing, to have one method for all Container. Additionally added Keyword class and Submission class, as well as made Keyword, Submission and Search children of Container.
Removed Search#method_missing and Submission#method_missing. Added Keyword.new and Submission.new.
Added proper Boolean recognition to Submission.new
Added Search#set_variables
Added Search#prev! and Search#next!.