1. improve n-fold quantification algorithm by introducing a minimal size for each fold. 2. automatically search for best n for n-fold algorithm. (#2167)

* 1. add quantification_fold parameter. 2. support quantification test in run.py.

* implement n-fold quantification

* open cl mem optimise, split with cpu codes.
fix a bug when some memory is not equal 4 .

* open cl mem optimise, split with cpu codes.   fix a bug when some memory is not equal 4  fix bad des

* fix ios CPU preprocess test=develop

* fix style test=develop

* Catch mobile exceptions test=develop

* code style format test=develop

close #1791

* add slice cpu op

* print error var name && print op position

* only InferShape when input shape has been changed

* apply input_dim_has_changed_ criterion only when model has one input vector

* add model obfuscate feature

* fix style

* fix array length bug

* add merge.sh to merge static library into one combined library

* disable OpenMP for iOS

* support creating tensor with raw pointer.

* fix style

* fix fpga compilation error

* marker1-anchor update

* concat-fetch bug

* add reshape2, transpose2, split GPU operator

* fix reshape2op && delete log

1.update CPUContext to probe CPU info 2.improve the performance of SlidingwindowConv3x3s1 and SlidingwindowConv3x3s2 (#1655)

* optimize GPU conv performance and structure

* add CL macro for test_conv_gpu

* fix build failure

* change funtion name

* change funtion name

* fix load_when_predict mode in opencl

* update concat and split kernel and related files in FPGA v2(v3) track

* update

* update

* update kernel and related files in FPGA v2 track

* update

* update

* update kernel and related files for static quantization in FPGA v2 track

* update

* update feed and fetch kernel in FPGA v2 track

* update concat and split kernel and related files in FPGA v2(v3) track

* update

* update

* update kernel and related files in FPGA v2 track

* update

* update

* FPGA refactor

* disable FPGAKD

* recover misdeleted code segment

Clear no persistable tensor array before predicting, fix crash when predicting with gpu debugging mode (#1548)

* Clear no persistable tensor array before predicting, fix crash when predicting with gpu debugging mode

* Fix code style