Each .cpp/.mm file includes corresponding header before any other...

... except Audacity.h

This forces us to make each header contain all forward declarations or nested
headers that it requires, rather than depend on context.

src/prefs/BatchPrefs.cpp

@@ -15,12 +15,12 @@ setting used in debugging batch (aka macros) processing.
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "BatchPrefs.h"
 
 #include <wx/defs.h>
 #include <wx/intl.h>
 #include <wx/textdlg.h>
 
-#include "BatchPrefs.h"
 #include "../Languages.h"
 #include "../Prefs.h"
 #include "../Project.h"

src/prefs/DevicePrefs.cpp

@@ -23,6 +23,7 @@ other settings.
 *//********************************************************************/
 
 #include "../Audacity.h"
+#include "DevicePrefs.h"
 
 #include <wx/defs.h>
 
@@ -38,8 +39,6 @@ other settings.
 #include "../ShuttleGui.h"
 #include "../DeviceManager.h"
 
-#include "DevicePrefs.h"
-
 enum {
    HostID = 10000,
    PlayID,

src/prefs/DirectoriesPrefs.cpp

@@ -16,6 +16,7 @@
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "DirectoriesPrefs.h"
 
 #include <math.h>
 
@@ -36,7 +37,6 @@
 #include "../Internat.h"
 #include "../ShuttleGui.h"
 #include "../widgets/ErrorDialog.h"
-#include "DirectoriesPrefs.h"
 
 enum {
    TempDirID = 1000,

src/prefs/EffectsPrefs.cpp

@@ -18,6 +18,7 @@
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "EffectsPrefs.h"
 
 #include "../Experimental.h"
 
@@ -29,8 +30,6 @@
 #include "../Prefs.h"
 #include "../ShuttleGui.h"
 
-#include "EffectsPrefs.h"
-
 #include "../Internat.h"
 
 EffectsPrefs::EffectsPrefs(wxWindow * parent, wxWindowID winid)

src/prefs/ImportExportPrefs.cpp

@@ -16,13 +16,13 @@
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "ImportExportPrefs.h"
 
 #include <wx/defs.h>
 
 #include "../Prefs.h"
 #include "../ShuttleGui.h"
 
-#include "ImportExportPrefs.h"
 #include "../Internat.h"
 
 ImportExportPrefs::ImportExportPrefs(wxWindow * parent, wxWindowID winid)

src/prefs/LibraryPrefs.cpp

@@ -17,6 +17,7 @@ MP3 and FFmpeg encoding libraries.
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "LibraryPrefs.h"
 
 #include "../Experimental.h"
 
@@ -30,7 +31,6 @@ MP3 and FFmpeg encoding libraries.
 #include "../widgets/HelpSystem.h"
 #include "../widgets/ErrorDialog.h"
 
-#include "LibraryPrefs.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 

src/prefs/MidiIOPrefs.cpp

@@ -24,6 +24,7 @@ other settings.
 *//********************************************************************/
 
 #include "../Audacity.h"
+#include "MidiIOPrefs.h"
 
 #include "../Experimental.h"
 
@@ -43,8 +44,6 @@ other settings.
 #include "../ShuttleGui.h"
 #include "../widgets/ErrorDialog.h"
 
-#include "MidiIOPrefs.h"
-
 enum {
    HostID = 10000,
    PlayID,

src/prefs/MidiIOPrefs.h

@@ -11,6 +11,7 @@
 
 #include "../Experimental.h"
 
+class wxTextCtrl;
 class ShuttleGui;
 
 #ifdef EXPERIMENTAL_MIDI_OUT

src/prefs/ModulePrefs.cpp

@@ -16,13 +16,13 @@ with names like mnod-script-pipe that add NEW features.
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "ModulePrefs.h"
 
 #include <wx/defs.h>
 #include <wx/filename.h>
 
 #include "../ShuttleGui.h"
 
-#include "ModulePrefs.h"
 #include "../Prefs.h"
 #include "../Internat.h"
 

src/prefs/ProjectsPrefs.cpp

@@ -17,6 +17,7 @@ handling.
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "ProjectsPrefs.h"
 
 #include <wx/defs.h>
 #include <wx/textctrl.h>
@@ -24,7 +25,6 @@ handling.
 #include "../Prefs.h"
 #include "../ShuttleGui.h"
 
-#include "ProjectsPrefs.h"
 #include "../Internat.h"
 
 ////////////////////////////////////////////////////////////////////////////////

src/prefs/ThemePrefs.cpp

@@ -29,13 +29,13 @@ Provides:
 *//********************************************************************/
 
 #include "../Audacity.h"
+#include "ThemePrefs.h"
 
 #include <wx/wxprec.h>
 #include "../Prefs.h"
 #include "../Theme.h"
 #include "../Project.h"
 #include "../ShuttleGui.h"
-#include "ThemePrefs.h"
 #include "../AColor.h"
 
 enum eThemePrefsIds {

src/prefs/WarningsPrefs.cpp

@@ -18,12 +18,12 @@
 *//*******************************************************************/
 
 #include "../Audacity.h"
+#include "WarningsPrefs.h"
 
 #include <wx/defs.h>
 
 #include "../ShuttleGui.h"
 
-#include "WarningsPrefs.h"
 #include "../Internat.h"
 
 ////////////////////////////////////////////////////////////////////////////////