single_line-option in AdA Timeline

[JStratil]

On mac v. 3.13 release 20210629 using the option "single_line:true" resulted in no annotations being displayed in that specific annotation type. I used different annotation types, e.g. FieldSize in package based on AdA template. (web browsers: safari, firefox tested). I had the same behavior with the 3.13 version on linux with opera.