Do not spellcheck roles

[anntzer]

In

:role:`text`

and

`text`:role:

(see http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#interpreted-text, both are equivalent), it would be nice if the role was not spellchecked (and possibly highlighted differently, perhaps fainter (of course that depends on the colorscheme and may be more controversial)).

[anntzer]

As a note for whoever tries to implement this (perhaps a future me), make sure not to confuse with field lists: http://docutils.sourceforge.net/docs/user/rst/quickref.html#field-lists