Edc

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- add migrations (edc-appointment,, edc-protocol-violation)
- refactor paths in edc_model, fix references in other modules

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- rebuild edc-data-manager

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- refactor paths in edc_model, fix references in other modules

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- refactor paths in edc_model, fix references in other modules
- add django-multisite-edc to install_requires, remove git+url
- configure new build for more edc modules

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- improve context sensitive showing of subject dashboard's unscheduled appt
button (edc-appointment, edc-subject-dashboard)
- reorder unscheduled appointments if a deletion breaks the sequence
(edc-appointment)
- cascade changed appointment visit_code_sequence to subject visit and
crf/requisition metadata (edc-appointment, edc-visit-tracking)
- declare metadata helper mixin as a model mixin also (edc-metadata)
- add metadata helper to appointment and visit tracking models

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- add SKIPPED_APPT appointment status to help handle routine
care where the next appointment may skip over the estimated
schedule.
- use settings attr to enable the use of appt_status=SKIPPED_APPT,
EDC_APPOINTMENT_ALLOW_SKIPPED_APPT_USING
- add signal to detect model that provides an appt date. Skip
over interim XXXX.0 appointments and update the target appointment
to the given date.