Modified file amenity-points.mss

Took out unnessesary icons and texts from amenity-points.mss
Finised styling icons

Removed majority of icons to appear on the map by deleteing them from CartoCSS code from file amenity-points.mss.
Removed icons png files are still avaiable in folder symbols. Didn't delete them for future use.

Also changed that road direction arrows will appear only from zoom level 17.