Separated Algebra tests from Choose tests.
Removed Choose operation.
Renamed Nil to Empty.
Converted score take a MetricData.
Cleaned up operations and operators. Removed BinaryOperator.
Split up oper tests from tree tests
Updated test names to get picked up by the test runner.
Add basic Cond code. str test is failing.
Tests passing.
Added repr test.
Added basic if condition test.
Added not condition and tests.
Moving stuff around.
Separated CondOperations from ScoreOperations.
Updated Operation to cleanly support UnaryOperations with code-time warnings.
Added OrOperator.
Added AndOperator.
Consolidated Operators into Operations.
Removed operators.
Refactored algebra operations intos separate module.