bugfix

[SCP1715]

I noticed a problem with qucs: when you try to drag a component from the components window to the workspace, the application crashes, although when you click everything works
I solved this problem in the following way:

`class iconCompInfoStruct
{
public:
int catIdx; // index of the component Category
int compIdx; // index of the component itself in the Category
iconCompInfoStruct()
{
catIdx = -1;
compIdx = -1;
qRegisterMetaTypeStreamOperators("iconCompInfoStruct");
};
iconCompInfoStruct(int cat, int comp)
{
catIdx = cat;
compIdx = comp;
qRegisterMetaTypeStreamOperators("iconCompInfoStruct");
}
};

QDataStream &operator<<(QDataStream &out, const iconCompInfoStruct &myObj)
{
out << myObj.catIdx;
out << myObj.compIdx;
return out;
}

QDataStream &operator>>(QDataStream &in, iconCompInfoStruct &myObj)
{
in >> myObj.catIdx;
in >> myObj.compIdx;
return in;
}`

[ra3xdh]

This may be related to #187 that is already fixed. Only platforms using Qt5.15 were affected. Are you still experience the crash using the latest snapshot from the current branch from Git? Are you experiencing crash on every drag'n'drop event? I cannot reproduce the crash on drag'n'drop event on my machine using both Qt5.9 and Qt5.15. What is your platform?

[SCP1715]

I tried the solution to the problem described in #187, but the program still crashes
I am using QT5.8.0 and VS 2017
Perhaps my solution is more versatile