Transition boolean data type to being modeled as a coded values instead of either boolean or numeric 0 & 1. This will allow for more graceful transition to TRUE/FALSE/UNKNOWN when concepts need to be remodeled or re-used.
- Add convenience methods to support boolean as coded values. Concept ids for TRUE and FALSE should be drawn from global properties org.openmrs.Concept.TRUE and org.openmrs.Concept.FALSE. If not defined, we could search Concept for concepts named "TRUE" and "FALSE" as a last result, I suppose.
- ConceptService: Concept getTrue() and Concept getFalse()
- Concept: Boolean getValueAsBoolean()
As a first pass, I'll see if I can make the changes to org.openmrs.Concept such that it's external behavior remains unchanged (so the existing code using concepts will not need to change).
Obviously, any DAO-level code that refers to boolean observations (possibly in reporting DAO?) will need to be changed.
