A Typographical Characters service

Hi Developers,

A question was recently posed to me about adding the copyright character 
(©) to the 'Typographical Characters' tool in kupu.  So I thought: why  
not have a Typographical Characters service that stores these useful 
non-keyboard chars?  With a service like this, site-admins can easily add 
chars, and developers can easily make this list available in their own 
products as well as in the forms-based editor.

So, while working on a refactor and upgrade of our silva-based cms, I wrote a 
service for this purpose.  It requires a modification to the typo chars tool 
in kupu, as well as small modifications to the various editor widgets 
(another li in the notes panel).  

Ultimately, I feel that this feature is useful beyond just my university's 
cms, so I'm wondering if something like this could eventually be included in 
Silva (like v1.3 or beyond)?

If infrae feels this would be useful, I'll be more than happy to provide a 
patch and instructions on installing.

Cheers,
Andy