1. The JNI_VERSION field is now included automatically in the generated JNI headers, relieving us of the burden of updating the version number in both java and native code.
2. We can update the JNI version with every non-compatible change of the JNI library API, not just once per release, giving us extra safety when users download and build LWJGL from SVN.
3. We can now avoid rebuilding natives if a particular release only
contains java changes. Currently, This is mostly a problem when Brian bumps the
external version prior a release and I forget to re-build the natives ;)
