[Kst] Potential crash...

[Andrew Walker]

There is a potential crash scenario when loading from a .kst file with
PSDs, Histograms, etc. These objects define a vectag property, a
vector which must already exist. If this is not the case then a null
KstVectorPtr results, which is then used in numerous places without
checking).

A better approach (instead of loading from the QDomElement in the 
constructor) would be to declare a default constructor and then a 
load(const QDomElement&) function which would return a bool to
indicate success or failure. If the object fails to load correctly it can
be deleted and an error message logged. At present Kst would crash.

Andrew