DolphinWX: Break up ConfigMain.cpp into separate classes

Prior to this, ConfigMain.cpp was a large (52KB) cpp file that contained all of the UI setting code.

This breaks up the config code into subclasses of wxPanel, which are then just instantiated to add to the settings wxNoteBook. This keeps all the settings categories separated from one another and also cleans up the code in general.

Source/Core/DolphinWX/Config/AudioConfigPane.h

@@ -0,0 +1,47 @@
+// Copyright 2015 Dolphin Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+#include <wx/arrstr.h>
+#include <wx/panel.h>
+
+class wxCheckBox;
+class wxChoice;
+class wxCommandEvent;
+class wxRadioBox;
+class wxSlider;
+class wxSpinCtrl;
+class wxStaticText;
+
+class AudioConfigPane final : public wxPanel
+{
+public:
+	AudioConfigPane(wxWindow* parent, wxWindowID id);
+
+private:
+	void InitializeGUI();
+	void LoadGUIValues();
+	void RefreshGUI();
+
+	void PopulateBackendChoiceBox();
+	static bool SupportsVolumeChanges(const std::string&);
+
+	void OnDSPEngineRadioBoxChanged(wxCommandEvent&);
+	void OnDPL2DecoderCheckBoxChanged(wxCommandEvent&);
+	void OnVolumeSliderChanged(wxCommandEvent&);
+	void OnAudioBackendChanged(wxCommandEvent&);
+	void OnLatencySpinCtrlChanged(wxCommandEvent&);
+
+	wxArrayString m_dsp_engine_strings;
+	wxArrayString m_audio_backend_strings;
+
+	wxRadioBox* m_dsp_engine_radiobox;
+	wxCheckBox* m_dpl2_decoder_checkbox;
+	wxSlider* m_volume_slider;
+	wxStaticText* m_volume_text;
+	wxChoice* m_audio_backend_choice;
+	wxSpinCtrl* m_audio_latency_spinctrl;
+};