Templates container

If no export templates already exist, a root-level container 'Templates' is added. The 'Templates' container's $OnAdd is set to $IsTemplate = true;. Also the built-in prototype 'HTML' ('HTML Template' in older versions) is added to the existing built-in Prototypes container or the latter container is also added. If a 'Templates' and/or 'Prototypes' container exists these are used for any newly added notes instead of creating new containers.