Show title in index instead of the filename

Example: if got a "graphicnovels.json" file, in the Index page you would have
a "graphicnovels" row linking to "graphicnovels.html".
With this commit, you can define a title in "graphicnovels.json" [e.g. "my favourite graphic novels"],
and in the Index page you'll get a "my favourite graphic novels" row instead of the previous "graphicnovels" row,
still linking to "graphicnovels.html".

The title is the same you'll show in the dedicated HTML generated page.