Fixed handling of text wrapping and a text layout corner case

Due to using QTextCursor::columnNumber() instead of
QTextCursor::positionInBlock(), a lot of code would not work correctly
when used with wrapped lines.

In addition, there was an issue with columnNumber() returning 0 right
after inserting a character before the last character of a line.

Reviewed-by: mae

src/plugins/qmljseditor/qmljseditor.cpp

@@ -1130,7 +1130,7 @@ bool QmlJSTextEditor::contextAllowsAutoParentheses(const QTextCursor &cursor, co
 
     Scanner tokenize;
     const QList<Token> tokens = tokenize(blockText, blockState);
-    const int pos = cursor.columnNumber();
+    const int pos = cursor.positionInBlock();
 
     int tokenIndex = 0;
     for (; tokenIndex < tokens.size(); ++tokenIndex) {