build: fix cyclic file dependencies that break the build on Linux

src/lib/settings/ApplicationSettings.cpp

@@ -1,5 +1,6 @@
 #include "settings/ApplicationSettings.h"
 
+#include "settings/migration/SettingsMigrator.h"
 #include "settings/migration/MigrationMoveKey.h"
 #include "utility/ResourcePaths.h"
 #include "utility/Status.h"

src/lib/settings/ProjectSettings.h

@@ -4,6 +4,7 @@
 #include <memory>
 #include <vector>
 
+#include "settings/migration/SettingsMigrator.h"
 #include "settings/LanguageType.h"
 #include "settings/Settings.h"
 

src/lib/settings/Settings.h

@@ -8,8 +8,7 @@
 #include "utility/ConfigManager.h"
 #include "utility/file/FilePath.h"
 
-#include "settings/migration/SettingsMigrator.h"
-#include "settings/migration/Migration.h"
+class Migration;
 
 class Settings
 {
@@ -60,14 +59,11 @@ protected:
 	void enableWarnings() const;
 	void disableWarnings() const;
 
-	friend bool SettingsMigrator::migrate(Settings* settings, size_t targetVersion) const;
-
 	std::shared_ptr<ConfigManager> m_config;
 
 private:
 	FilePath m_filePath;
 
-	friend SettingsMigrator;
 	friend Migration;
 };
 

src/lib/settings/migration/SettingsMigrator.cpp

@@ -1,5 +1,6 @@
 #include "settings/migration/SettingsMigrator.h"
 
+#include "settings/migration/Migration.h"
 #include "settings/Settings.h"
 
 SettingsMigrator::SettingsMigrator()

src/lib/settings/migration/SettingsMigrator.h

@@ -11,8 +11,6 @@ class Settings;
 class SettingsMigrator
 {
 public:
-	static SettingsMigrator createApplicationSettingsMigrator();
-
 	SettingsMigrator();
 	virtual ~SettingsMigrator();