* [SCHEDULE]enable partition const loop with build flag (#719)

    * enable partition loop with build flag

    * add a testcase, and modify LoopPartition related cases

*     * add document for split_const_loop

* [IRbuild]Support automatically Name Loop Variable in IRBuilder (#719)

    * add idx_num in class

* using typical index [i, j, k] first, then i_suffix

* keep inputs names

* fix lint

* improve comment of name

* fix lint

* [SCHEDULE]Improve bound deduce for loop partition (#743)

    * add divided checking when deducing

    * related testcase

* fix

* * transform LE and GE first
* remove is_equal
* modify testcase for edge cases checking

* * fix comment

* * fix lint

* * apply transformation form LT -> LE, GT -> GE

* * fix lint

* simplify code and testcase

* add negative co-efficient case

* More complicated cases

* add testcase

* simplify testcase

* comment case for now

* fix testcase