Move RuntimeMetaData.VERSION field to the top of the source file
Relax the default version mismatch listener to only throw an exception if the major or minor version components do not match
Update the assignment of Tool.VERSION (fixes #634)

* Reference RuntimeMetaData.VERSION so there are fewer version numbers to update during a release
* Assign the value in a static initializer so it's not a compile-time constant
Updated comments to clarify recent changes in code
Merge pull request #635 from sharwell/relax-versioning

Relax versioning