Allow to easily tag Persons for comments

[BigRoy]

Issue

A great aspect of commenting on CG-Wire is the capability of being able to tag a specific person to notify them about a change or question. It would be great if we can extend this functionality to qtazu.

Initially I did a prototype as can be seen in the README:

However the functionality wasn't perfect, as deleting/backspacing names would still remove the text per character whereas it would be much more powerful the text field could identify the tag and consider it a single "block" that needs to be removed. Additionally we'll need to make sure that the comment to CG-Wire actually preserves the tag.

Approach

1. Design a Python Qt implementation that supports adding tags to a text field and managing them easily.
2. Make sure the tag is correctly send to CG-Wire through gazu so that CG-Wire know who was tagged.