Loading ocontours added

[tomasprinda]

core.py

• I created class ContourMask modified class AnnotatedScan so that it holds 2 instances of ContourMask. One for i-contour -> imask, the other o-contour ->omask.

parse.py

• I created get_contour_mask() which takes care of creating ContourMask() objects
• I created load_annotated_scan() which takes care of loading one single AnnotatedScan() which simplified method load_patient_scans()

I adjusted tests to reflect the changes

Wrong data!!!
I found out o-contours for patient with DICOM_ID=SCD0000501 are shifted so I am skipping loading data for this patient. See experiments/test_imask_inside_omask_without_skipping/

To make sure to catch these kind of error I created test_imask_inside_omask()