Remove unnecessary #include-s from .cpp files...

... Unnecessary because transitively included.

But each .cpp file still includes its own .h file near the top to ensure
that it compiles indenendently, even if it is reincluded transitively later.

src/xml/XMLFileReader.cpp

@@ -21,8 +21,6 @@
 
 #include <string.h>
 
-#include "../Internat.h"
-
 XMLFileReader::XMLFileReader()
 {
    mParser = XML_ParserCreate(NULL);

src/xml/XMLTagHandler.cpp

@@ -24,9 +24,6 @@
 #include "../Audacity.h" // for USE_* macros
 #include "XMLTagHandler.h"
 
-#include "../MemoryX.h"
-#include "../Internat.h"
-
 #ifdef _WIN32
    #include <windows.h>
    #include <wx/msw/winundef.h>
@@ -36,7 +33,6 @@
 #include <wx/arrstr.h>
 #include <wx/filename.h>
 
-#include "../SampleFormat.h"
 #include "../Track.h"
 
 // Length check.  Is in part about not supplying malicious strings to file functions.

src/xml/XMLWriter.cpp

@@ -33,8 +33,6 @@ the general functionality for creating XML in UTF8 encoding.
 
 #include <string.h>
 
-#include "../Internat.h"
-
 //table for xml encoding compatibility with expat decoding
 //see wxWidgets-2.8.12/src/expat/lib/xmltok_impl.h
 //and wxWidgets-2.8.12/src/expat/lib/asciitab.h