Replace a temp variable with an inquiry

A temp variable "totalAmount" in "statement" method is replaced with an
inquiry. A new method "getTotalCharge" is added.
Replace a temp variable with an inquiry

A temp variable "frequentRenterPoints" is replaced with an inquiry. A
new method "getTotalFrequentRenterPoints" is added.
Add a new method

A new method "htmlStatement" is added. "statement" method is arranged.
Fix bugs

Modify minor bugs.
Relocate methods

getChage() and getFrequentRenterPoints in Rental class are moved into
Movie class.