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_events/messages/juce_DeletedAtShutdown.h

@@ -0,0 +1,65 @@
+/*
+  ==============================================================================
+
+   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.
+
+   The code included in this file is provided under the terms of the ISC license
+   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
+   To use, copy, modify, and/or distribute this software for any purpose with or
+   without fee is hereby granted provided that the above copyright notice and
+   this permission notice appear in all copies.
+
+   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
+{
+
+//==============================================================================
+/**
+    Classes derived from this will be automatically deleted when the application exits.
+
+    After JUCEApplicationBase::shutdown() has been called, any objects derived from
+    DeletedAtShutdown which are still in existence will be deleted in the reverse
+    order to that in which they were created.
+
+    So if you've got a singleton and don't want to have to explicitly delete it, just
+    inherit from this and it'll be taken care of.
+
+    @tags{Events}
+*/
+class JUCE_API  DeletedAtShutdown
+{
+protected:
+    /** Creates a DeletedAtShutdown object. */
+    DeletedAtShutdown();
+
+    /** Destructor.
+
+        It's ok to delete these objects explicitly - it's only the ones left
+        dangling at the end that will be deleted automatically.
+    */
+    virtual ~DeletedAtShutdown();
+
+
+public:
+    /** Deletes all extant objects.
+
+        This shouldn't be used by applications, as it's called automatically
+        in the shutdown code of the JUCEApplicationBase class.
+    */
+    static void deleteAll();
+
+private:
+    JUCE_DECLARE_NON_COPYABLE (DeletedAtShutdown)
+};
+
+} // namespace juce