CO311: More classes with various member function implementations

Example	animal.h	animal.cpp	driver.cpp	Notes
1				Basic class definition
2				“Inline” function definitions
3				Special “return reference” type
4				friend operator<< and making it work with cout

Example	roman.h	roman.cpp	driver.cpp	Notes
1				Mixing “Inline” function definitions with separate implementation
2				returning a string instead of displaying it
3				increment operators (i++, ++i)
4				friend operator<< and making it work with cout

Example	length.h	length.cpp	driver.cpp	Notes
1				Putting it all in one place
2				Same thing, but 2 files.
3				Same thing, but 3 files
4				friend operator<< and making it work with cout
5				increment operator (i++)
6				One multi-purpose data member
7				Use static member to keep track of what gets incremented