resolved: rename "SearchDomains" property in the Manager interface to "Domains"

resolved: rename "SearchDomains" property in the Manager interface to "Domains"

Another property name fuck-up. The property contains both search and routing
domains and hence should be exposed as "Domains" rather than "SearchDomains".

The counterpart in the Link object was correctly named, and the
SetLinkDomains() and SetDomains() setter calls too, hence let's get this right,
too.

(Yepp, a minor API break actually, but given that this was so far not
documented, and only 3 days public let's fix this now)