add cache for PythonPrimEvaluator. Be careful that
 the infer function of PythonPrimitive in python code should
 be idempotent.

Signed-off-by: Hoai Linh Tran h00472437 <hoai.linh.tran@huawei.com>

Add optimizer checking: For a group of passes in "optimizer", if flagged then it will check and collect the newly generated nodes without types (i.e. abstract() == nullptr).
Before calling Renormalize(), the optimizer will check if there is any node needed retyping. If not the Renormalize pass will not be called.
Add checking for non-null abstract but still needs renorm;
Add flags to Substitution to help watching Renormalize

Simpler pass result checker, change Bool to Enum type

Merge pull request !135 from penn/fix_free_morphism_error

Signed-off-by: leonwanghui <leon.wanghui@huawei.com>

use unpack graph primitive instead

add testcases for all grad interface

remove debug log

format code

remove dumpfuncgraph

resolve clang-format

resolve reviews

resolve cpplint

fix review

Signed-off-by: leonwanghui <leon.wanghui@huawei.com>