Lightweight Java Game Library Code

Windows: Don't use a non-portable anonymous struct in contex.h

Windows: Cleanup

Windows: Moved NativeSysImplementation.java to WindowsSysImplementation.java and moved some native code to java.

Windows: Move more of Display.getVersion to java

Windows: Added NULL check to malloc in display.c

Windows: Forgot display.c in last commit

Fixed SysTest.java

Windows: Don't release clipboard data before use

Windows: Removed unused variable from display.c

Split the external LWJGL version from the internal version of the native JNI library. The internal JNI version is now an integer. This has multiple advantages over the old way:

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 ;)