lua : document new API fields
lua : make the wiki doc the dev version and officialise the user manual as the stable version
lua : add versionning information to the lua documentation

this information is only used by the wiki version of the API doc

the usermanual version will catch up at a later point
lua : document the new field to register_storage
lua : allow plugs for documentation generation

only implemented on the wiki side for the moment,

Allows better typing in doc