Fix Javadoc problems

* Removed Javadoc comments that were basically empty
  (they only contained the blank template generated by the IDE, which
  was never filled out and in most cases outdated)
* Removed incorrectly placed Javadoc comments with only an @author line
  (Git tracks authorship anyway)
* Fixed some HTML syntax errors in Javadoc comments
* Changed some comments' ASCII art so they are not incorrectly
  considered Javadoc comments