Added option to start search without any terms

[bertrandgorge]

Added a new option "search on empty queries" that, when set to true, allows WikiSearchFront to start the search even when no terms are given.

{{#WikiSearchFrontend:
|size=10
|search on empty queries=true
|facets=4
...
}}

[robis24]

When no terms are entered WikiSearchFront will add an * to the search term query, so this should already work by default. Maybe you accounted this problem in a version where the WikiSearch extension stopped altering the query string and WikiSearchFront did not alter the query string yet, could this be the case or am I missing the use case?

[bertrandgorge]

Ah, that's possible. I've just tried with the current master branch and I confirm the correct behaviour, so you can just ditch this PR ! Thanks !