Create indices according to specs

This PR creates indices [according to the specs defined in the wiki] (https://github.com/geoadmin/service-sphinxsearch/wiki/Search-Requirements)

- Remove all unnecessary stuff
-- Remove quadindex where it's not needed (swisssearch)
-- Remove detail where it's not needed (feature search for queryable layers)

- Use prefix for quadindex instead of infix (feature search for both queryable and searchable layers)
- Use infix of length 2 for all searches with detail search

- Make sure that all feature searches contain the same attributes

- Add lon/lat attributes in feature indices. This allows [`SetGeoAnchor`](http://sphinxsearch.com/docs/manual-2.0.9.html#api-func-setgeoanchor) filtering and sorting

- Some refactoring to have clearer code

- Adapted test script to allow testing of geoanchor (see below for test command)

These changes result in [smaller indices and faster index creationg](https://github.com/geoadmin/service-sphinxsearch/wiki/Infix,-Prefix,-Star-Search)

Note that the current indices on the dev machine are created with this.

Testing command for GeoAnchor:

`python test.py -i ch_astra_ivs-reg_loc -e "@geom_quadindex 0*" -ga 46.95109 7.43863 -s "@geodist ASC"`

This will return all features on the index (geom_quadindex 0* returns all features) but sorted by distance to the reference (which is 600000/200000). Note that geoAnchor works with lat/lon only.