C++: support smart splitting of strings.

If 'enter' is pressed while the cursor is in the middle of a string,
the string is ended at the current cursor position, and a new string
is started on the next line.  This makes it very easy to split a long
string onto multiple lines.

In addition, Shift+Enter insert an escape in the string, to continue the
string at the beginning of next line.

A setting can be used to enable or disable this option.

Change-Id: Ia5f3c6989fc00d40d06bc4fe1182fe8b1318f565
Reviewed-by: Francois Ferrand <thetypz@gmail.com>
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/texteditor/autocompleter.cpp

@@ -332,6 +332,12 @@ bool AutoCompleter::isInComment(const QTextCursor &cursor) const
     return false;
 }
 
+bool AutoCompleter::isInString(const QTextCursor &cursor) const
+{
+    Q_UNUSED(cursor);
+    return false;
+}
+
 QString AutoCompleter::insertMatchingBrace(const QTextCursor &cursor,
                                            const QString &text,
                                            QChar la,