Rudder

I removed some more warning with some more -Y option. Now, one can use:

-deprecation -explaintypes -feature -unchecked -Ypartial-unification  -language:existentials -language:higherKinds -language:implicitConversions 
-Xlint:_,-nullary-unit,-missing-interpolator -Yno-adapted-args -Ywarn-dead-code -Ywarn-extra-implicit -Ywarn-inaccessible -Ywarn-infer-any 
-Ywarn-nullary-override -Ywarn-numeric-widen -Ywarn-unused:imports -Ywarn-unused:locals -Ywarn-unused:privates

And still only get the 5 deprecation warning that are hard to remove.

(we can't yet add these option to our main scala build because rudder-commons / scala-ldap / ldap-inventory have a lot of warnings)