Deprecate Iterators

Several modules and functions use Iterators, Filter, and Mapper. These classes will be deprecated and should replaced with the standard Java Stream API.

Notable methods:

• Evaluator#evaluateElements()
• Corpus#documentIterator()
• Document#sectionIterator()
• Corpus#sectionIterator()
• DocumentModule#documentIterator()
• SectionModule#sectionIterator()
• LibraryModel#generateDocumentation()
• XMLDocumentationResourceBundle#getKeys()