Discuss inheritance earlier in course

[smasher164]

Presumably, students taking 2150 have had some prior exposure to class-based inheritance. By discussing its usage in C++ at a higher level earlier in the course, they will be free to use it. For example in lab 3, they can inherit from a LinkedList to implement a Stack, or in lab 5 inherit from a BinarySearchTree to implement an AVLTree.

Discussion of virtual method tables can still be deferred to the assembly lab, if we feel that vtables are better understood in the context of compiler internals and code generation. However, features like multiple inheritance and dynamic dispatch can still be discussed at the language level.