measurement change pt

[sprivite]

Implements measurement change phenotype

[sprivite]

need to discuss:

1. what to do when measurements are on same date (phenotype does not have intra-day resolution)
2. different kinds of return dates. return_date = 'second' just means second event, but many pairs of events might satisfy the filters and which of these do we return? right now, all are returned

[a-hartens]

1. measurements on the say day should be handled by the measurementpheontype; we either do daily_mean/daily_median or no value aggregation. However, we are not able to pick up lab changes occurring on the same day. so currently we do not support time stamps.
2. return_date is the concept of multiple events which fulfill your criteria, and which one you should return the date of. There is something else happening with phenotypes that require multiple events to become a positive event e.g. multiple occurrences, lab change, and computation graph phentoypes (logic, score, arithmetic). For these we have been using return_date first, last, but should consider having a new keyword arguement. component_date_select, return_date stays the same