Fixed default import from external module and added more tests for export assignment.
Merge declarations -- supported merging module with class, interface and function.
Create expected file when it not exists using actual result for content in tests.
Split test runner to utils and configuration add configuration for test on DefinitelyTyped repo.
Split test runner to utils and configuration add configuration for test on DefinitelyTyped repo.
Some fixes after run on declarations from DefinitelyTyped repo.

- support vars without type annotation;
- support use Array as GenericType in vararg param;
- fix failing when try print ClassKind;
- improve error messages;
- stub code for correct printing ObjectType.
Minor: improve declarations for TS Compiler -- made TypeAnnotationSyntax nullable in some places.
Merge interfaces and modules.
Start the support merging variable with interface and module.
Allow varargs without type annotation.