Changed time:Duration to time:TemporalDuration, which is more appropriate since it allows different representations of the duration.

Added the representation of Points and Polygons from GeoSPARQL. This makes redundant the use of the WGS84 ontology, so it is removed.
Closes #1.

Removed the Pesticides instance. On the one hand, pesticides can be both chemical and microbial. On the other hand, it is out of scope to categorize chemical compounds according to their intended use (e.g., pesticide, fertilizer, etc.).

Renamed two properties according to the last SAREF fix.