* Add hard_swish, ctc_align and reciprocal op, test=develop
* Move some activation ops to extra, test=develop

add cuda kernel.

abs, tanh, elementwise_sub

* add backend

* add kernel

* add grad kernel

* add mean op, test=develop

* split forward and backward, test=develop

* Fix act bug for opencl kernel. test=develop

* add print ActToStr. test=develop

* remove print code. test=develop

* fix leakyrelu and tanh compute error, test=develop

* delete extra file, test=develop

* reset act

* fix conflict and readme, test=develop

* fix ios run error, test=develop

* Support multiple types for XPU and NPU op bridges

* Add lookup_table, gather, slice, stack and scale op bridges for supporting BERT

* Fix the definition of lookup_table kernel for X86

test=develop

* fix step rnn model run bugs test=develop

* add assign_value op, arm kernel and test, add fluid_type, test=develop

* add hard_sigmoid, test=develop