Added parameter so filename is included in the partial mapping

[McGern]

Added useFileNameForPartial to allow the partial to register with the full path and the filename.

Rationale:
Using the library with nested partials works well but it does become quite verbose especially when you are using partial blocks e.g.

Instance where there is a components folder with multiple sub folders all containing named components within a same named folder

{{#> core-components/wrapper/wrapper }}
inside
{{/core-components/wrapper/wrapper}}

The inclusion of this parameter will allow both the nested partial name and the filename only partial name to be registered, with the side-effect that any partials with the same filename will be will re-registered with the last instance found.