Doc: new QML code syntax check messages

Edit the new messages and add them to the Qt Creator Manual.

Change-Id: Ib494fd20861473ea824dd0d4260cad621c4081a4
Reviewed-by: Tim Jenssen <tim.jenssen@theqtcompany.com>
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
MacroExpander: Minor interface cosmetics

Change-Id: Id6963a6ef29478db85c92c4d557f823502e173a5
Reviewed-by: Orgad Shaneh <orgads@gmail.com>