Lightweight Java Game Library Code

Mac OSX: removed agl

Fixed mac opengl loading bug

let extgl_Open throw the exception to gain more information about the failure

Linux: removed redundant last_z from Mouse.c. Mac: Compile fixes. Use NSAddImage for loading GL library

Added initialization to all global symbols, to please MacOSX

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Converted native code from C++ (.cpp files) to C (.c files), thus avoiding an annoying dependency on the standard C++ library on Linux. We weren't using any particular C++ features anyway.