NOTE: This breaks compat with previous previous versions since Zola made a
breaking change in 0.19 and imho it's not worth trying to support previous
versions too.
There's some css rules for which prepending the name of the menu item as
set in the config causes the <a> element to appear shifted down compared
to the other <a> elements of the menu. I might have a look later, but
for now this enables only the appeareance of the RSS icon, discarding
entirely the name of the link.
This adds support for showing a tiny RSS svg badge in the top menu in
case the user added a menu_item that looks like this:
`{name = "", url = "$BASE_URL/$FEED_FILENAME"}`
This also requires that the user has a config.toml that contains the
following entries:
generate_feed = true
feed_filename = "rss.xml"
author = "your name here"
* Noting that (as of 0.14) zola does not pass much of a context when
rendering the 404 page, so things like current URL/path aren't
available
* To work around this the `menu` macro has been split into `menu_for`
which accepts a parameter for which item is active.
* The previous macro continues to work as is, forwarding the results of
figuring out which item is active to the new `menu_for` macro
* The added 404 page will then use the `menu_for` macro and pass in a
blank item
