A simple wrapper for the system function fork(2).
The advantage of using this class instead of fork directly is, easyness, robustness and readability due to less code. The constructor executes fork(2) and does error checking. The destructor waits for the child process, which prevents the creation of zombie processes. The user may decide to deactivate it or waiting explicitely to receive the return status, but this has to be done explicitely, which helps robustness.