Use tabs, add missing license header
Updated the documentation and improved the flexibility for future use of RuntimeMetaData.checkVersion
* Redefine checkVersion as version mismatch detection instead of a compatibility check

* Update notification behavior to notify callback listeners instead of throwing an exception
* Remove the distinction between regular and "extended" semantics
* Alter the default version mismatch behavior to throw an exception instead of write a message to System.err

* Ensure that DefaultListener is always the last listener notified (since it throws an exception)
* Update the checkVersion documentation to more clearly describe the scenarios for which version mismatches are detected
Merge pull request #601 from sharwell/versioning-docs

Versioning updates and documentation