Copy-Ctor/Assignment-Op of libember Types missing/erroneous

[simongysi-lawo]

A proper implementation of the copy constructor and/or assignment operator of many classes of libember is missing. Futhermore, most of the classes are deriving from libember::dom::Node and offers thereby the virtual clone() method. This method is not properly overriden at many places.

Beside lacking the feature to copy an Ember+ tree, it's erroneous and causes runtime problems (memory leaks, double delete, wrong parent relationship...). Either implement the copy constructor and assignment operator correctly of these types or pohibite copy/assignment.

I strongly recommend to implement them, because there are use cases for it, like implementing a proxy which forwards Ember+ messages - right now, cloning messages is an extra task, which has be done outside the library. This causes major maintainability troubles.

Examples of wrong copy constructor / assignment operator are found in nearly every Glow type, e. g. libember::glow::GlowNode (and the whole hierarchy upwards).