Updates to the search facility for datasets

The search interface has been updated. Now the map used in the search box supports more map projections, including a southern and northern hemisphere map. Furthermore, the search interface has been further restructured and prepared for more faceted searchs (e.g. by institutions) in the future. The business logic supproting transformations has also received some upgrades, but many of these will first be fully visible once the backend services are updated as well.