Global Namespace Operator for functions

[volsa]

Is your feature request related to a problem? Please describe.
#1442 introduces the global namespace operator for variables. Codesys does support the operator on functions also, however, meaning the following is code is valid

FUNCTION_BLOCK fb
  // ...
  METHOD foo
    // ...
  END_METHOD


  // ...
  .foo(); // This will call the function `foo` defined in the global namespace, if it exists
  // ...
END_FUNCTION_BLOCK