cover against abnormal cases
"convert" is now a reserved keyword.
henceforth the client list takes types instead of simple class names. The old (standard Eiffel) behaviour is retained though.
types-as-clients: eiffeldoc support
types-as-clients: new germ
now actual full types can actually be used as clients (proof in next commit)
tightening exports (using types as clients)
latest grem, with working types as clients