Updates to Hands On C++

The updates below are arranged most-recent-to-least-recent:

Exercise Update Description Date

Lab 4 Modified code files to include the promised code. 2003/10/17

Lab 9 Changed operation table to use istream::get(char) to read a character instead of >>. 2003/12/9

Lab 11 Changed a Simply() to simplify(). 2003/12/9

Exercise	Update Description	Date
Lab 4	Modified code files to include the promised code.	2003/10/17
Lab 9	Changed operation table to use `istream::get(char)` to read a character instead of `>>`.	2003/12/9
Lab 11	Changed a `Simply()` to `simplify()`.	2003/12/9