Update RemoteSpaceDock18.cs with new namespace and new code

Updated the namespace (of course) and made some code changes. Instead of using RequestResource() to check part availability, I just ask each PartResource for its amount property. It allows me to query individual warehouses, instead of the rootPart. This way a conglomeration of vessels joined by docking ports can all provide RocketParts when building, presuming at least one vessel has a SpaceDock. Previously, the rootPart would only provide access to warehouse inventory if that warehouse was an original component of the rootPart's vessel.