Start using init makeNode, makeChain, etc methods

Use interfaces::Init::make* methods instead of interfaces::Make*
functions, so interfaces can be constructed differently in different
executables without having to change any code. (So for example
bitcoin-gui can make an interfaces::Node pointer that communicates with
a bitcoin-node subprocess, while bitcoin-qt can make an interfaces::Node
pointer that starts node code in the same process.)

src/qt/bitcoin.h

@@ -27,6 +27,9 @@ class PlatformStyle;
 class SplashScreen;
 class WalletController;
 class WalletModel;
+namespace interfaces {
+class Init;
+} // namespace interfaces
 
 
 /** Main Bitcoin application object */
@@ -51,6 +54,8 @@ public:
     void createWindow(const NetworkStyle *networkStyle);
     /// Create splash screen
     void createSplashScreen(const NetworkStyle *networkStyle);
+    /// Create or spawn node
+    void createNode(interfaces::Init& init);
     /// Basic initialization, before starting initialization/shutdown thread. Return true on success.
     bool baseInitialize();
 
@@ -69,7 +74,6 @@ public:
     void setupPlatformStyle();
 
     interfaces::Node& node() const { assert(m_node); return *m_node; }
-    void setNode(interfaces::Node& node);
 
 public Q_SLOTS:
     void initializeResult(bool success, interfaces::BlockAndHeaderTipInfo tip_info);
@@ -103,7 +107,7 @@ private:
     const PlatformStyle *platformStyle;
     std::unique_ptr<QWidget> shutdownWindow;
     SplashScreen* m_splash = nullptr;
-    interfaces::Node* m_node = nullptr;
+    std::unique_ptr<interfaces::Node> m_node;
 
     void startThread();
 };