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/processors/juce_ProcessorDuplicator.h

@@ -0,0 +1,99 @@
+/*
+  ==============================================================================
+
+   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
+{
+
+/**
+    Converts a mono processor class into a multi-channel version by duplicating it
+    and applying multichannel buffers across an array of instances.
+
+    When the prepare method is called, it uses the specified number of channels to
+    instantiate the appropriate number of instances, which it then uses in its
+    process() method.
+
+    @tags{DSP}
+*/
+template <typename MonoProcessorType, typename StateType>
+struct ProcessorDuplicator
+{
+    ProcessorDuplicator() : state (new StateType()) {}
+    ProcessorDuplicator (StateType* stateToUse) : state (stateToUse) {}
+    ProcessorDuplicator (const ProcessorDuplicator&) = default;
+    ProcessorDuplicator (ProcessorDuplicator&&) = default;
+
+    void prepare (const ProcessSpec& spec)
+    {
+        processors.removeRange ((int) spec.numChannels, processors.size());
+
+        while (static_cast<size_t> (processors.size()) < spec.numChannels)
+            processors.add (new MonoProcessorType (state));
+
+        auto monoSpec = spec;
+        monoSpec.numChannels = 1;
+
+        for (auto* p : processors)
+            p->prepare (monoSpec);
+    }
+
+    void reset() noexcept      { for (auto* p : processors) p->reset(); }
+
+    template<typename ProcessContext>
+    void process (const ProcessContext& context) noexcept
+    {
+        jassert ((int) context.getInputBlock().getNumChannels()  <= processors.size());
+        jassert ((int) context.getOutputBlock().getNumChannels() <= processors.size());
+
+        auto numChannels = static_cast<size_t> (jmin (context.getInputBlock().getNumChannels(),
+                                                      context.getOutputBlock().getNumChannels()));
+
+        for (size_t chan = 0; chan < numChannels; ++chan)
+            processors[(int) chan]->process (MonoProcessContext<ProcessContext> (context, chan));
+    }
+
+    typename StateType::Ptr state;
+
+private:
+    template <typename ProcessContext>
+    struct MonoProcessContext : public ProcessContext
+    {
+        MonoProcessContext (const ProcessContext& multiChannelContext, size_t channelToUse)
+            : ProcessContext (multiChannelContext), channel (channelToUse)
+        {}
+
+        size_t channel;
+
+        typename ProcessContext::AudioBlockType getInputBlock()  const noexcept       { return ProcessContext::getInputBlock().getSingleChannelBlock (channel); }
+        typename ProcessContext::AudioBlockType getOutputBlock() const noexcept       { return ProcessContext::getOutputBlock().getSingleChannelBlock (channel); }
+    };
+
+    juce::OwnedArray<MonoProcessorType> processors;
+};
+
+} // namespace dsp
+} // namespace juce