Reworked the processing of the page-data

Reworked the processing of the page-data

Automatically generated pages can be overwriten in the manually defined
menu. Overwriting a URI will result in the changing of the name of the
page. Child-pages be kept in place, if present. If an automatically
generated page is overwriten in the manually defined menu, it will not
be removed form the original menu, but its breadcrumb-data will reflect
the position of the manually defined entry.

Implementation:
The data is read into a map. The unnamed menus will be read in last,
because this are usually the manually defined menus. If an URI is encountered
again, the last read version of the defined page will win and overwrite the
previously read definition, but the defined child-pages will not be touched.