Tags

- Includes breaking changes to v1.x.y Sorry. All changes were made to move forwards with the iFDO concept towards a 
  robust metadata schema. Hence, there exists now a schema definition file for iFDOs, annotations and the provenance 
  format. This required to make the changes explained below in the other version changes of 
- It is now recommended to provide ifdo files in JSON format
- The field image-provenance has been added to document the agents, entities and activities that led to the creation 
  of the image set. This field is inspired by the definition of w3-prov
- The ambiguity of having two options for altitude / depth has been removed by dropping the image-depth field 
  entirely (you may use it if you like but the renamed field image-altitude-meters is required as well)
- Many fields that used to be strings are now objects to provide not only a value but also a link to external 
  resources, e.g. ```image-platform: {name: PFM-XYZ, uri: https://foobar/PFM-XYZ}```. Others fields that are affected: 
  image-sensor, image-license, image-context, image-project, image-event, image-pi
- The ``image-related-material`` field was added to reference information in external resources that relates to this 
  iFDO (e.g. cruise reports).
- The four fields image-set-[min,max]-[latitude,longitude]-degrees were added to define a bounding box within which all 
  images of the iFDO reside
- It is now required, that the iFDO ``image-set-header`` part includes one representative value for each of these 
  fields: ``image-datetime``, ``image-latitude``, ``image-longitude``, and ``image-altitude-meters``
- Some field names changes to either be properly spelled or include the unit name into the field name, e.g. for 
  ``image-altitude`` which is now called ``image-altitude-meters`` and ``image-area-square-meter``which is now called  
  ``image-area-square-meters`.