Add find_patients/studies/series/instances and query_orthanc functions

[gacou54]

Add the following functions, that allow to find patients, studies, series or instances with a query on DICOM tags and provided labels.

New features:

• functions, that allow to find patients, studies, series or instances with a query on DICOM tags and provided labels
  • find_patients()
  • find_studies()
  • find_series()
  • find_instances()
  • query_orthanc()
• Improved Patient, Study, Series and Instance
  • Now based on the Resource object
  • Resources now have the lock parameter, which locks locally the state of the Resource at the first information query.
  • Add the following attributes and methods
  • .labels, .add_label(label) and .remove_label(label)
  • .is_stable
  • .last_update
  • Deprecate Patient.is_protected() in favour of Patient.protected
  • Deprecate Patient.set_to_(un)protected() in favour of Patient.protected = True/False
  • Patient.studies calls Orthanc to create a list of patient's studies
  • Study.series calls Orthanc to create the study's series
  • Series.instances calls Orthanc to create the series' instances
• Modify and expose the retrive_and_write_(patients/patient/study/series/instance) functions
  • Rename retrieve_(patient/study/series/instance) to retrieve_and_write_(patient/study/series/instance)

Refactoring:

• Simplification of the find() function. Does not change the functionality.