Add clear() to RelOptPlanner. PlannerImpl.transform() call clear().

PlannerClear : add uint test case wip.

add method to add traitDef to planner.

clear rulequeue status in planner.

Change the order of traits importance.

Revert "Change the order of traits importance."

This reverts commit 4b6ae327c9f142133aec45489042b78d2f68d039.

Replace contains with subsumes check.

Add unit test for cases where transform() is called twice with different rulesets and target convention. The test case will fail if not call planner.clear().

Planner clear: fix a code style issue in unit test case.

Planner clear: remove some code change for RelTrait

Planner clear: code clean up.

Planner clear: code style check change.
Code formatting, and add comments.
Absorb RelOptPlanner.clearRules() method into clear().