OPENNLP-1406 Enhance JavaDoc in opennlp.tools.parser package

[mawiesne]

Change

• adds missing JavaDoc
• improves existing documentation for clarity
• removes superfluous text
• removes orphaned (commented) code fragments in ..parser.treeinsert.ParserEventStream
• fixes a missing variable assignment in ParserCrossValidator (a hidden bug)
• adds 'final' modifier where useful and applicable
• adds 'Override' annotation where useful and applicable
• fixes several typos
• corrects some inconsistencies in the opennlp.tools.chunker and opennlp.tools.langdetect package

Tasks

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