* fix elementwise_op bug when the shape of input y is 1, test=develop

* fix elementwise ops bug when the shape of input y is 1, test=develop

* add stack op and add reduce_mean op and their unit tests

* modify stack op output name and modify the for loop in reduce_mean op

* add HasAttr for slice op

* add yolo_box_compute cuda

* move multiclass_nms(arm) to host

* add lod in scale op

* add yolo_box_cuda cmake config

* modify shuffle_channel_fuse and transpose_softmax_transpose_fuse to support run ssd model. test=develop

* reshape and transpose op don't have xshape output.

* modify yolo_box_compute_cuda, use tensor to manage cuda memory test=develop

* add yolo_box use kernel test=develop

ad ops for faster rcnn, including affine_channel, anchor_generator, generate_proposals and roi_align (#1895)

* add ops for faster rcnn

* disable test for generate_proposals and roi_align, test=develop

* remove .swp file

* remove log in tensor slice

* finish the unit test for roi_align, test=develop

* modify cast op, test=develop

* modify cast op and remove warning in argmax_test, test=develop

* test=develop add matmul_op

* use lite::arm::math::sgemm func to implement matmul

* test=develop  pre-commit command to run clang-format

* Revert "test=develop  pre-commit command to run clang-format"

This reverts commit 3f56474f.

* test=develop pre-commit command to run clang-format

add model_run_test_image
    add range_max_quant op
    add flatten op
    add flatten2 op
fix:
    fix density_prior_box density_size type from float to int
    fix prior_box and density_prior_box some check for get_attr
test=develop