#81 Class members are often not properly initialized at construction

[Gert Wollny]

In many cased the class members of certain classes are not properly initialized at construction time. Since the Set* method check these values to track the changes, the according if constructs compare to uninitialized values. (valgrind is an excellent tool to find such bugs.)
The attached patches fix some of these problems by properly initializing member variables at construction time.

The incentive to use initialization over assignment within the constructor comes from Sutter at al. (www.gotw.ca), #48.