Revise my answer to Exercise 3.2.

This commit comes with a major revision, included is the following 2 files:

     	Exercise_3.2.scm
	Test_of_Exercise_3.2.scm

Thank you!
							Lawrence R. Amlord
							  Sept 12th, 2013
							  Xi'an, China
Revise my answer to Exercise Exercise 3.4.

Included are the following 2 files:

	Exercise_3.4.scm
	Test_of_Exercise_3.4.scm

Thank you!
							Lawrence X. Amlord
							  Sept 13th, 2013
							  Xi'an, China
Add my answer to Exercise 3.5.

Included are the following 2 files:

	Exercise_3.5.scm
	Test_of_Exercise_3.5.scm

Thank you!
							Lawrence R. Amlord
							  Sept 14th, 2013
							  Xi'an, China
Add the code in section 3.1.2.

Included is the following file:

	3.1.2_The_Benefits_of_Introducing_Assignment.scm

Thank you!
							Lawrence R. Amlord
							  Sept 14th, 2013
							  Xi'an, China
Add my answer to Exercise 3.6.

Included is the following file:

	Exercise_3.6.scm

Thank you!
							Lawrence X. Amlord
							  Sept 14th, 2013
							  Xi'an, China
Add code in section 3.1.3.

Included is the following file:

	3.1.3_The_Costs_of_Introducing_Assignment.scm

Thank you!
							Lawrence X. Amlord
							  Sept 14th, 2013
							  Xi'an, China
Add my answer to Exercise 3.7.

Included are the following 2 files:

	Exercise_3.7.scm
	Test_of_Exercise_3.7.scm

Thank you!
							Lawrence X. Amlord
							  Sept 15th, 2013
							  Xi'an, China
Add my answer to Exercise 3.8.

Included is the following file:

	Exercise_3.8.scm

Thank you!
							Lawrence X. Amlord
							  Sept 15th, 2013
							  Xi'an, China