Cleanup type reflections.
Fix AND, OR and Coalesce operators. Lazy evals.

(WIP) PlanoutContext. Experiment struct.

(WIP) struct Experiment --> struct Interpreter

(WIP) Methods for the Interpreter struct

(WIP) Operator::execute takes interpreter as arg.

(WIP) Add support / test for namespaces
Adding basic Namespace support

- Create namespace with a fixed segment length.
- Add experiments to a namespace
- Allocate experiments to segment slot based on sample operator.
- Select segment (and associated experiment) based on randomInteger
  operator.