Use type aliases FilePath, FilePaths...

... for wxString and wxArrayStringEx, holding file paths (absolute or relative,
directory or plain file); to be replaced later with different types

(not yet using std::vector, becase of some uses of wxArrayString::Index with
two arguments)

src/FileNames.cpp

@@ -24,6 +24,8 @@ used throughout Audacity into this one place.
 
 #include "Experimental.h"
 
+#include "MemoryX.h"
+
 #include <wx/defs.h>
 #include <wx/filename.h>
 #include <wx/intl.h>
@@ -46,7 +48,7 @@ used throughout Audacity into this one place.
 static wxString gDataDir;
 
 bool FileNames::CopyFile(
-   const wxString& file1, const wxString& file2, bool overwrite)
+   const FilePath& file1, const FilePath& file2, bool overwrite)
 {
 #ifdef __WXMSW__
 
@@ -71,7 +73,7 @@ bool FileNames::CopyFile(
 #endif
 }
 
-bool FileNames::HardLinkFile( const wxString& file1, const wxString& file2 )
+bool FileNames::HardLinkFile( const FilePath& file1, const FilePath& file2 )
 {
 #ifdef __WXMSW__
 
@@ -106,7 +108,8 @@ wxString FileNames::TempDir()
 }
 
 // originally an ExportMultiple method. Append suffix if newName appears in otherNames.
-void FileNames::MakeNameUnique(wxArrayString &otherNames, wxFileName &newName)
+void FileNames::MakeNameUnique(FilePaths &otherNames,
+   wxFileName &newName)
 {
    if (otherNames.Index(newName.GetFullName(), false) >= 0) {
       int i=2;
@@ -123,7 +126,7 @@ void FileNames::MakeNameUnique(wxArrayString &otherNames, wxFileName &newName)
 
 //
 // Audacity user data directories
-wxString FileNames::AutoSaveDir()
+FilePath FileNames::AutoSaveDir()
 {
    wxFileName autoSaveDir(FileNames::DataDir(), wxT("AutoSave"));
    return FileNames::MkDir(autoSaveDir.GetFullPath());
@@ -144,7 +147,7 @@ wxString FileNames::LowerCaseAppNameInPath( const wxString & dirIn){
    return dir;
 }
 
-wxString FileNames::DataDir()
+FilePath FileNames::DataDir()
 {
    // LLL:  Wouldn't you know that as of WX 2.6.2, there is a conflict
    //       between wxStandardPaths and wxConfig under Linux.  The latter
@@ -182,12 +185,12 @@ wxString FileNames::DataDir()
    return gDataDir;
 }
 
-wxString FileNames::ResourcesDir(){
+FilePath FileNames::ResourcesDir(){
    wxString resourcesDir( LowerCaseAppNameInPath( wxStandardPaths::Get().GetResourcesDir() ));
    return resourcesDir;
 }
 
-wxString FileNames::HtmlHelpDir()
+FilePath FileNames::HtmlHelpDir()
 {
 #if defined(__WXMAC__)
    wxFileName exePath(PlatformCompatibility::GetExecutablePath());
@@ -207,43 +210,43 @@ wxString FileNames::HtmlHelpDir()
 #endif
 }
 
-wxString FileNames::LegacyChainDir()
+FilePath FileNames::LegacyChainDir()
 {
    // Don't force creation of it
    return wxFileName{ DataDir(), wxT("Chains") }.GetFullPath();
 }
 
-wxString FileNames::MacroDir()
+FilePath FileNames::MacroDir()
 {
    return FileNames::MkDir( wxFileName( DataDir(), wxT("Macros") ).GetFullPath() );
 }
 
-wxString FileNames::NRPDir()
+FilePath FileNames::NRPDir()
 {
    return FileNames::MkDir( wxFileName( DataDir(), wxT("NRP") ).GetFullPath() );
 }
 
-wxString FileNames::NRPFile()
+FilePath FileNames::NRPFile()
 {
    return wxFileName( NRPDir(), wxT("noisegate.nrp") ).GetFullPath();
 }
 
-wxString FileNames::PlugInDir()
+FilePath FileNames::PlugInDir()
 {
    return FileNames::MkDir( wxFileName( DataDir(), wxT("Plug-Ins") ).GetFullPath() );
 }
 
-wxString FileNames::PluginRegistry()
+FilePath FileNames::PluginRegistry()
 {
    return wxFileName( DataDir(), wxT("pluginregistry.cfg") ).GetFullPath();
 }
 
-wxString FileNames::PluginSettings()
+FilePath FileNames::PluginSettings()
 {
    return wxFileName( DataDir(), wxT("pluginsettings.cfg") ).GetFullPath();
 }
 
-wxString FileNames::BaseDir()
+FilePath FileNames::BaseDir()
 {
    wxFileName baseDir;
 
@@ -267,7 +270,7 @@ wxString FileNames::BaseDir()
    return baseDir.GetPath();
 }
 
-wxString FileNames::ModulesDir()
+FilePath FileNames::ModulesDir()
 {
    wxFileName modulesDir(BaseDir(), wxEmptyString);
 
@@ -276,32 +279,32 @@ wxString FileNames::ModulesDir()
    return modulesDir.GetFullPath();
 }
 
-wxString FileNames::ThemeDir()
+FilePath FileNames::ThemeDir()
 {
    return FileNames::MkDir( wxFileName( DataDir(), wxT("Theme") ).GetFullPath() );
 }
 
-wxString FileNames::ThemeComponentsDir()
+FilePath FileNames::ThemeComponentsDir()
 {
    return FileNames::MkDir( wxFileName( ThemeDir(), wxT("Components") ).GetFullPath() );
 }
 
-wxString FileNames::ThemeCachePng()
+FilePath FileNames::ThemeCachePng()
 {
    return wxFileName( ThemeDir(), wxT("ImageCache.png") ).GetFullPath();
 }
 
-wxString FileNames::ThemeCacheHtm()
+FilePath FileNames::ThemeCacheHtm()
 {
    return wxFileName( ThemeDir(), wxT("ImageCache.htm") ).GetFullPath();
 }
 
-wxString FileNames::ThemeImageDefsAsCee()
+FilePath FileNames::ThemeImageDefsAsCee()
 {
    return wxFileName( ThemeDir(), wxT("ThemeImageDefsAsCee.h") ).GetFullPath();
 }
 
-wxString FileNames::ThemeCacheAsCee( )
+FilePath FileNames::ThemeCacheAsCee( )
 {
 // DA: Theme sourcery file name.
 #ifndef EXPERIMENTAL_DA
@@ -311,7 +314,7 @@ wxString FileNames::ThemeCacheAsCee( )
 #endif
 }
 
-wxString FileNames::ThemeComponent(const wxString &Str)
+FilePath FileNames::ThemeComponent(const wxString &Str)
 {
    return wxFileName( ThemeComponentsDir(), Str, wxT("png") ).GetFullPath();
 }
@@ -319,7 +322,7 @@ wxString FileNames::ThemeComponent(const wxString &Str)
 //
 // Returns the full path of program module (.exe, .dll, .so, .dylib) containing address
 //
-wxString FileNames::PathFromAddr(void *addr)
+FilePath FileNames::PathFromAddr(void *addr)
 {
     wxFileName name;
 
@@ -413,7 +416,7 @@ wxString FileNames::FindDefaultPath(Operation op)
       return DefaultToDocumentsFolder(key).GetPath();
 }
 
-void FileNames::UpdateDefaultPath(Operation op, const wxString &path)
+void FileNames::UpdateDefaultPath(Operation op, const FilePath &path)
 {
    if (path.empty())
       return;
@@ -427,14 +430,14 @@ void FileNames::UpdateDefaultPath(Operation op, const wxString &path)
 wxString
 FileNames::SelectFile(Operation op,
            const wxString& message,
-           const wxString& default_path,
-           const wxString& default_filename,
+           const FilePath& default_path,
+           const FilePath& default_filename,
            const wxString& default_extension,
            const wxString& wildcard,
            int flags,
            wxWindow *parent)
 {
-   return WithDefaultPath(op, default_path, [&](const wxString &path) {
+   return WithDefaultPath(op, default_path, [&](const FilePath &path) {
       return FileSelector(
             message, path, default_filename, default_extension,
             wildcard, flags, parent, wxDefaultCoord, wxDefaultCoord);