Change OperationDetail to not store complex objects in STL containers (#729139)

OperationDetail was storing its children in a std::vector.  This means they
can be moved around in memory arbitrarily, going through indeterminate
lifetimes.  This is generally a bad thing for any non trivial object and
in the case of OperationDetail, it created havoc with the way it maintains
pointers between parent/child objects for signal connections.  It will now
keep only pointers to children in a std::vector instead, so their lifetime
can be controlled, fixing various crashes.

Bug 729139 - Refactor OperationDetail to address random behavior