Add support for "Enter" for creating new tags

[sdrenth]

When typing a non-existent tag you need to click on "assign" to have the tag created and assigned. When I click enter nothing happens and the text is being cleared. It would be nice if you could instantly add and assign a new tag when clicking on Enter key.

[patrickatwsrn]

Works for me in 1.12.0. Please check and confirm.