Add "multiple/repeatable input" component

[tkotosz]

I was thinking about a component which would render an input field and an "add" button, which would allow to add any number of new text fields. Something like this one:
https://www.sanwebe.com/2013/03/addremove-input-fields-dynamically-with-jquery
The component would insert the text-field values as yaml array to the widget config.

Nice to have:

• configure min/max number of fields
• configure field type which will be duplicated (e.g. text, select, etc)
• if field type is configurable then maybe allow custom field types (like DatePicker)

[tkotosz]

ah this one is even better: https://github.com/Rhyzz/repeatable-fields
see demo here: http://www.rhyzz.com/repeatable-fields.html