Editors: Move auto-completion code out of the editor

This is basically a continuation of the commits which
refactor code out of the base text editor. For instance,
36fa1de4c6 and
3a684586fa.

Also removed the doXXXX() forwarding methods.

src/plugins/texteditor/normalindenter.cpp

@@ -60,10 +60,10 @@ NormalIndenter::~NormalIndenter()
 // for additional block being inserted. It might be possible
 // to do in 2 steps (indenting/wrapping)}
 //
-void NormalIndenter::doIndentBlock(QTextDocument *doc,
-                                   const QTextBlock &block,
-                                   const QChar &typedChar,
-                                   BaseTextEditor *editor)
+void NormalIndenter::indentBlock(QTextDocument *doc,
+                                 const QTextBlock &block,
+                                 const QChar &typedChar,
+                                 BaseTextEditor *editor)
 {
     Q_UNUSED(typedChar)