Relabel "Call type" to "Signal type" and add KW whistles and clicks

[scottveirs]

As an authenticated annotator,
I want to be able to label not only SRKW calls, but also SRKW whistles and clicks,
So that I can create test and training data for non-call binary classifiers or multiclass models.

Here is the current UI:

Proposed solutions

1. Add an "Other field" to the existing UI and instruct annotators to add the non-call signal label in the comment field
2. Rename the "Call type" drop-down UI element to the more generic "Signal type" and then add "whistle" and "click" as choices.