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_dsp/maths/juce_SpecialFunctions.h

@@ -0,0 +1,68 @@
+/*
+  ==============================================================================
+
+   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
+{
+namespace dsp
+{
+
+/**
+    Contains miscellaneous filter design and windowing functions.
+
+    @tags{DSP}
+*/
+struct SpecialFunctions
+{
+    /** Computes the modified Bessel function of the first kind I0 for a
+        given double value x. Modified Bessel functions are useful to solve
+        various mathematical problems involving differential equations.
+    */
+    static double besselI0 (double x) noexcept;
+
+    /** Computes the complete elliptic integral of the first kind K for a
+        given double value k, and the associated complete elliptic integral
+        of the first kind Kp for the complementary modulus of k.
+    */
+    static void ellipticIntegralK (double k, double& K, double& Kp) noexcept;
+
+    /** Computes the Jacobian elliptic function cd for the elliptic
+        modulus k and the quarter-period units u.
+    */
+    static Complex<double> cde (Complex<double> u, double k) noexcept;
+
+    /** Computes the Jacobian elliptic function sn for the elliptic
+        modulus k and the quarter-period units u.
+    */
+    static Complex<double> sne (Complex<double> u, double k) noexcept;
+
+    /** Computes the inverse of the Jacobian elliptic function sn
+        for the elliptic modulus k and the quarter-period units u.
+    */
+    static Complex<double> asne (Complex<double> w, double k) noexcept;
+};
+
+} // namespace dsp
+} // namespace juce