Releasing OpenGL ES Resources

Releases the resources created by "InitializeGLState"

Frees the OpenGL handles used in the program, and the two shaders.

 	glDeleteShader(_fragmentShader);
 	glDeleteShader(_vertexShader);
 	glDeleteProgram(_shaderProgram);
 

Delete the vertex buffer object as it is no longer needed.

 	glDeleteBuffers(1, &_vertexBuffer);