fix macOS build (following Projucer changes made in Windows, which removed /Applications/JUCE/modules from its headers). move JUCE headers under source control, so that Windows and macOS can both build against same version of JUCE. remove AUv3 target (I think it's an iOS thing, so it will never work with this macOS fluidsynth dylib).

modules/juce_gui_basics/mouse/juce_ComponentDragger.h

@@ -0,0 +1,102 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2017 - ROLI Ltd.
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
+   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
+   27th April 2017).
+
+   End User License Agreement: www.juce.com/juce-5-licence
+   Privacy Policy: www.juce.com/juce-5-privacy-policy
+
+   Or: You may also use this code under the terms of the GPL v3 (see
+   www.gnu.org/licenses).
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+
+//==============================================================================
+/**
+    An object to take care of the logic for dragging components around with the mouse.
+
+    Very easy to use - in your mouseDown() callback, call startDraggingComponent(),
+    then in your mouseDrag() callback, call dragComponent().
+
+    When starting a drag, you can give it a ComponentBoundsConstrainer to use
+    to limit the component's position and keep it on-screen.
+
+    e.g. @code
+    class MyDraggableComp
+    {
+        ComponentDragger myDragger;
+
+        void mouseDown (const MouseEvent& e)
+        {
+            myDragger.startDraggingComponent (this, e);
+        }
+
+        void mouseDrag (const MouseEvent& e)
+        {
+            myDragger.dragComponent (this, e, nullptr);
+        }
+    };
+    @endcode
+
+    @tags{GUI}
+*/
+class JUCE_API  ComponentDragger
+{
+public:
+    //==============================================================================
+    /** Creates a ComponentDragger. */
+    ComponentDragger();
+
+    /** Destructor. */
+    virtual ~ComponentDragger();
+
+    //==============================================================================
+    /** Call this from your component's mouseDown() method, to prepare for dragging.
+
+        @param componentToDrag      the component that you want to drag
+        @param e                    the mouse event that is triggering the drag
+        @see dragComponent
+    */
+    void startDraggingComponent (Component* componentToDrag,
+                                 const MouseEvent& e);
+
+    /** Call this from your mouseDrag() callback to move the component.
+
+        This will move the component, using the given constrainer object to check
+        the new position.
+
+        @param componentToDrag      the component that you want to drag
+        @param e                    the current mouse-drag event
+        @param constrainer          an optional constrainer object that should be used
+                                    to apply limits to the component's position. Pass
+                                    null if you don't want to contrain the movement.
+        @see startDraggingComponent
+    */
+    void dragComponent (Component* componentToDrag,
+                        const MouseEvent& e,
+                        ComponentBoundsConstrainer* constrainer);
+
+private:
+    //==============================================================================
+    Point<int> mouseDownWithinTarget;
+
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ComponentDragger)
+};
+
+} // namespace juce