fix pasted tags that include single field delimiter

Hi!

This change solves a problem where pasting a string containing the single field delimiter into the tag input field would create a single tag containing the entire string. The expected behaviour would be to create multiple strings split by the single field delimiter.

Example:
The single field delimiter is a space character. The entered string (by pasting) is "hello world". Previously, this would create one tag called "hello world". After this change, there would be one tag called "hello" and another called "world".

How's this sound to you?

Thanks
Martin