Search as specified in specs

This PR changes the search view to correspond to the search as [defined in the specs](https://github.com/geoadmin/service-sphinxsearch/wiki/Search-Requirements)

- It removes unneeded stuff, mainly combinations of bbox/searchtext/features that are not needed.

Added a new type: `features`. Types now do the following:

# locations
Combines swisssearch and feature search. Swisssearch uses searchtext only (no bounding box) and feature search uses searchtext and bounding box (quadindex). Results are combined

# features
Searches for all features in given bounding box. Does not require a searchText

# layers
As before

This works well with the indices created with [this pull request](https://github.com/geoadmin/service-sphinxsearch/pull/1/) So if you merge this PR into master, make sure that the indices the search service is using are created using the configuration in the pull request above.