change to use __add__ operation instead ds.concat

Merge pull request !1130 from jiangjinsheng/flatten

Merge pull request !1156 from YuJianfeng/master

Merge pull request !1171 from fary86/adjust_onnx_related_uts

Merge pull request !1113 from dengwentao/rts

Merge pull request !1163 from YuJianfeng/bn_fusion_with_cast

Merge pull request !1015 from candanzg/me_with_shape

Merge pull request !1026 from peixu_ren/custom_pp_ops

Merge pull request !1149 from panyifeng/fix_pylint

Merge pull request !1146 from Etone.Chan/master

Merge pull request !1084 from SanjayChan/04quant

Merge pull request !1089 from ghzl/add-get-lr-base-on-parameter

Merge pull request !1139 from JesseKLee/timing_hole

Merge pull request !1131 from xulei/filter_op

Merge pull request !1069 from 李鸿章/context_manager

Merge pull request !1094 from zhouneng/add_vm_support_l2normalize

Signed-off-by: candanzg <zhangshucheng@huawei.com>

Merge pull request !1121 from lihongkang/master

Merge pull request !1124 from YuJianfeng/master

Merge pull request !999 from liyong126/mindrecord_file_list

Merge pull request !1091 from chenweifeng/cast

Merge pull request !1079 from lianliguang/convert-to-AICPU-when-AiCore-not-supported-kernel

Merge pull request !1042 from jinyaohui/clean_pylint

Merge pull request !1082 from hewei/support_cont_break

To handle 'break' and 'continue' statement, a loop context is pushed
to a stack before we parse the loop body, and pop it after body parsed.
When a 'break', 'continue' statement is encountered, we retrieve current
loop contex from the stack, and let the current block jump to the end
block or header block;

For 'break' statement, we added an extra 'end_block' follow the 'after_block',
because 'after_block' is called from a ContionalJump in 'header_block', it can
not be set as jump target from other place. to support 'break', we let loop
body jump to the 'end_block' at the 'break' point. and 'after_block'
maybe a good place to handle loop 'else' clause in the future.

Handle 'pass' is simple, just bypass it when doing parse.