Only send Set operations which update those attributes once all entities
have been properly created on the server, and we know their ids.
This, together with other $eid fixes in cyexport, fixes the issue with
wielded and worn entities not properly being restored.
This uses the same importing code as Ember, and allows for import of
both entities, minds and types. The code in EntityImporterBase.*
should be kept synchronized with the Ember version.
This is provided as a new command, instead of added to the existing
cycmd executable. This is by design, to make it easier for users.
Export and import of entities are one of the most basic functions,
especially for any new user, and should therefore be provided as easy as
possible.
