Suppress cast warnings
Covariant overrides for Scenario members
Use getter instead of deprecrated public field
Add missing comment
Suppress non-applicable warning
Tidy, refactor
Add "Provider" interfaces to ...Sets. ...Maps can also act as providers, returning themselves.
Merge branch 'master' of https://github.com/calpath/model-elements
Make SensorSet optional
Update to also use Joel's trick on serialized JSON objects containing union types

Converting "model_elements_base" to "model_elements" with string of JSON
file. Ugly hack continues.
Allow null value for SensorSet
Regenerate MM scenarios with updated schema for FreewayContextConfig
Merge pull request #34 from andrewbts/master

Add "Provider" interfaces to ...Sets. ...Maps can also act as providers, returning themselves.