RFC: reduce number of alias parameters

[Björn JACKE]

On 2017-12-11 at 11:58 +0000 Rowland Penny via samba-technical sent off:
> read only = No
> writeable = Yes

personally I would like this alias also to disappear but I was afraid to
propose something revolutionary like this. Maybe for this one we should
deprecate it first and give it a grace time of one or two leases. For the other
parameters I think this is not required becasue they are rarely used compared
to this one.

Björn