Inheritance, access modifiers
### Homework
#### Project 1
Write a class **PString** that is derived from the **STL** string class. The
**PString** class should add a member function which determines whether the
string is a palindrome.
#### Project 2
Write a class named **EncryptableString** that is derived from the **STL** string
class. The **EncryptableString** class adds a member function which encrypts the
string contained in the object by replacing each letter with its successor in
the ASCII ordering.
Assume that the only characters to be encrypted in an **EncryptableString**
object are letters (a → z and A → Z), and numbers (0 → 9), and that the
successor of 'z' is 'a', the successor of 'Z' is 'A', and the successor of '9'
is '0'. Other characters should not be encrypted, such as spaces and
punctuation.
### Lab
#### Project 1
Complete the People At MCC classes
#### Project 2
Write classes representing animals, birds, and dogs
