preparation for more unit tests

After change, the smoother will smooth any given reference line without truncate.
The behavior will be more transparent behavior.

* not a useful base class
* confusing with hdmap path.h

the problem is because LaneWaypoint is not set in hdmap::Path.
fixed the broken unit tests

unify function names

optimizers.

* use std::string as ObjectId
* remove LRUCache

fixed apollo::planning::TrajectoryPoint issues. DO NOT KNOWN why it can still be compiled before... (#232)

fixed apollo::planning::TrajectoryPoint issues.

varified that the smoothing algorithm works

* easier for coding
* less error prone for building ST graph.