* add support to gcc8, add docker env test=develop

* fix the random compilation failure on windows 

* remove unused FLAGS_warpctc_dir

test=develop

* remove FLAGS_warpctc_dir

test=develop

test=develop

* "fix cuda9 error"

* "change commit id"

* "remote git tag"

* Update source files.

* Update headers

* Update

* Update

* Update

* Update

* Fix a CMake dependency

* It will sightly faster compile and make warpctc compile
well on CUDA 9 and GCC 5.5

* Add Seq2BatchFunctor, which will be used in WarpCTCOp.

* Implement WrapCTCFunctor and WrapCTCKernel.

* Add unittest of warpctc_op.

* Modify the check_output inferface in python unittest framework to allow check a subset of outputs.

* Use absolute offset lod in warpctc_op and related functors.

* Refine the comments of warpctc_op.

* The new python unittest supports checking a subset of the outputs, so revoke the previous change.

* Rename the transform from LoDTensor to Tensor with shape [max_sequence_length, num_sequences, sequence_width] to PaddingSequenceFunctor.

* Update to the newest codes.

* Rename the PaddingSequenceFunctor to PaddingLoDTensorFunctor and remove the computation of dimensions out of the functos.

* Support the build for multiple architectures at one cmake command (iOS).

* Update the documentations.

Recover the mistakenly deleted WARPCTC variable in cmake.

So that they can be found when paddle is built as a add_subdirectory project in another project.

Fix case-sensitiveness