Updating Maven version numbering, directory structure

[Sean Owen]

Maven's standard semantic versioning scheme calls for version numbers like x.y.z. Right now the project's versions are like x.y -- 2.2, 2.3. I'm changing the scheme starting now, so that for example, the current snapshot release is now 2.3.0-SNAPSHOT, not 2.3-SNAPSHOT. This may affect people depending on the snapshot, or, on future releases. 

I'm also finally going to fix the directory structure to match Maven conventions. For example, source code will be in src/main/java, not src/. Test data will be in src/test/resources, not test/data. This will make for a very big looking patch and might mess with your local changes or branches, although the changes are just SVN moves, so should be mergeable.