v2.0.0

• (Major updates with non backward compatible API changes)
• All Observation methods based on Image and blocks (through Observation.stack)
• All physical Image attributes returning astropy.units.Quantity
• Documentation transferred in new repo (hosted with github pages at https://lgrcia.github.io/prose-docs)
• new catalogs blocks (storing in Image.catalogs) with plate-solving features
• CleanBadPixels block
• All dates attributes harmonized to datetime objects