Add (somewhat general) multiple language doc support, and added java language doc for 19 pages under 'Writing WiredTiger applications in Java', with references to new java example files.

Known deficiencies: from the Java documentation, there are about 40 @ref 'C' versions of documentation, that in most cases should be to the Java pages. That can be done on a case by case basis (will do next). Javadoc @refs (pulled in via @copydoc) also do not yet reference these pages or java examples. I haven't figured out how to hook into @copydoc to get this done. I guess it's possible to do a post processing step on the doc tree.

Wanted to get this out for review in the meantime, it's rather usable as is.