Beautifier: Move formatting tools to TextEditor

Formatting is moved from Beautifier plugin to formattexteditor.h/.cpp.
Diff and Differ classes are extracted from DiffEditor to Utils
to prevent extra TextEditor dependencies.

This change will make possible to use formatCurrentFile
and similar functions not only from Beautifier code.

Change-Id: Ic5ca668afe88f4e9376d49e6bd3594807172b0dd
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/diffeditor/diffeditorplugin.cpp

@@ -29,7 +29,6 @@
 #include "diffeditorcontroller.h"
 #include "diffeditordocument.h"
 #include "diffeditorfactory.h"
-#include "differ.h"
 
 #include <QAction>
 #include <QFileDialog>
@@ -50,10 +49,12 @@
 #include <texteditor/texteditor.h>
 
 #include <utils/algorithm.h>
+#include <utils/differ.h>
 #include <utils/mapreduce.h>
 #include <utils/qtcassert.h>
 
 using namespace Core;
+using namespace Utils;
 
 namespace DiffEditor {
 namespace Internal {