Add new tokens: SETUP, EXERCISE, VERIFY, TEARDOWN and PhaseDescription
Add new constituents: FourPhaseTest and its children
Implement unimplemented methods in ParseTreeToAstVisitor. Introduce Phase class.
Make Assrtion, Execution and LetBindings be subtypes of Action.
Fix: Keywords should be placed before Identifier.
Fix: `Do` and `Let` can appear in the middle of line.
Add tests for new AST elements
Increase coverage
Fix: FourPhaseTest should be a subtype of Definition
Change the grammar more restrictive: let bindings can appear only in setup phase.
Make verification phase to be mandatory in four phase test
Add VerifyPhase AST type for veryfy phase (used instead of using Phase)
Fix: s/actions/assertions/
Fix arguments for TestMethod contructor
Fix test data
Include before/after actions in TestMethod
Add ActionStatement
Add translateFourPhaseTest (partial implementation)
Fix arguments for TestMethod constructor
Fix arguments for TestMethod constructor