DPUB spec role definitions should use a standardized prefix such as "dpub-*"

[cookiecrook]

Each of these roles should use the dpub- prefix to avoid confusion and name collision with the main ARIA spec. If they are useful enough for mainstream adoption, we can coordinate the names when the roles are pulled into the main ARIA spec. e.g. dpub-chapter would very likely be adopted as an unprefixed ARIA role "chapter", but "dpub-locator" is still just a link and would likely never be brought into the main spec. Authors can specify these today as role="dpub-locator link" (this is a valid ARIA 1.0 syntax) and the UAs will fall back to the link role appropriately, while still allowing parsers access to the dpub-specific role.

[cookiecrook]

Looks like this was a double-post. Dupe of Issue #36