In the middle of chapater 3-6.
Merge branch '3-6' of https://github.com/Incarnation-p-lee/dsaaa into trunk

Conflicts:
	archive/coverage.info
	archive/homework.rept
	archive/report.tar.gz
	inc/defs.h
  Merge temporary work 3-6 to trunk
  1. Finished chapter 3-6, poly add.