WIP: Resolve "Complete state vector new data structure?"

Closes #287 (closed)

Continues in !358 (closed)

include/core/problem/problem.h

@@ -44,8 +44,10 @@ class Problem : public std::enable_shared_from_this<Problem>
 
     // TODO move somewhere below
     public:
-        StateComposite  getStateComposite() const;
-        StateComposite  getStateComposite(const TimeStamp& _ts) const;
+    bool  getStateComposite(StateComposite& _state) const;
+    bool  getStateComposite(const TimeStamp& _ts, StateComposite& _state) const;
+    StateComposite  getStateComposite() const;
+    StateComposite  getStateComposite(const TimeStamp& _ts) const;