Downgrade node types version because of observable type
compatibility issue.
Remove unsupported generics from empty calls.
Use observable create for API call wrapping
becasue of non compatible type when using
observable from promise.
Add frame generator because it was removed
from RxJS 6.
Request non nested sequence_key property for performance reasons.
Handle non exisiting sequences by returning empty sequence as
fallback in API.
Add tests for fallback logic.
Extending Error does not create instances of the created error classes.
Act accordingly in unit test error type checks.
Upgrade three js typings for compatibility.
Error derived classes does not need to create stack trace
explicitly.
Use tilde ranges for ts dev deps for future compatibility.
