v. 0.5.3
  - TSPHP-660 Rename token CASTING_ASSIGN to CAST_ASSIGN:
    - new parser tokens included
    - amended the different tree walkers
    - added new version of parser component
  - TSPHP-690 Improve code coverage typechecker
  - removed copyright notices in package-info.java files (left over)
  - added improved version of copyAntlr
  - added new version of common component
  - TSPHP-503 TypeCheckerController is too big
    - created IReferencePhaseController and moved methods accordingly
    - Renamed Definer to DefinitionPhaseController to be consistent with the other phase controllers
    - Created IVisibilityChecker which contains the access check which is used in the reference phase as well as in the type check phase
    - modified tests where necessary
  - deleted TypeCheckerControllerIsReturningTest because it was a left  over (return check was simplified in v. 0.5.3)
  - Improved ATypeSystemTest concerning extensibility
  - Removed several hidden dependencies and moved them to the constructor of the corresponding classes
  - TypeSystem had an init method which was called by the TypeCheckerController. Quite ugly, removed it. Yet, there is still a cyclic dependency between TypeSystem and SymbolFactory