[Feature Request] Expose more utility functions

[LadislavBohm]

What feature or change would you like to see made?

I'm trying to implement my own annotation tool that is based on LengthTool. When looking at it's source code it uses some very useful utility functions that are not exposed publicly. For example these functions I'm not able to import and use in my own project:

1. triggerAnnotationCompleted
2. triggerAnnotationModified

Is it by design or is it ok to export those as well?

Why should we prioritize this feature?

It helps people correctly implement annotation tools. It ensures same behavior as already existing tools.

[sedghi]

You can create a PR and I will merge it