* Add FP16 option in save_combine_op

* Fix casting issue

We should improve our test isolation before raising the
level of parallelism.

This reverts commit 0446220e.

Reason:

Rerun failed test hides flaky test.
Flaky test can be bugs, for example, race condition.
Test shouldn't be flaky, if a test is flaky, it should be fixed.

* CI: rerun failed tests.

* fix check style error.

* init refactor

* init

* update some comment

* fix build

* fix errorrr

* fix bug

* fix comment

* update

We need to figure out if tensorrt
use row-major or col-major for tensor
layerout inorder to do conversion.

Do not use ctor

* Reduce line of codes.
* We can use virtual function for Maker now.
* The implementation does not care what maker holds, it is easier to
refactor later.

Rename MatDim to MatDescriptor