Implement missing buildIndex(const Matrix<ElementType>& dataset) for KDT...

flann::KDTreeCuda3dIndexParams params;
params["input_is_gpu_float4"]=true;
//the following two lines work in current version
flann::Matrix<float> matrix_gpu(pointer_gpu, point_num, 3, 4*sizeof(float));
flann_index_.buildIndex(matrix_gpu);

// but not these two lines, due to the missing of buildIndex(const Matrix<ElementType>& dataset) in KDTreeCuda3dIndex class
//flann::Index<flann::L2<float> > flannindex( params );
//flann_index_.buildIndex(matrix_gpu);

Also, on page 16 of the manual (http://www.cs.ubc.ca/research/flann/uploads/FLANN/flann_manual-1.8.4.pdf), the stride parameter should be 4*sizeof(float).