We first check if there's any non-transient entity apart from the root
world. If so, the world is already is populated and we won't import;
unless the user supplied either the flag "--clean" which will reset the
world, or "--merge" which will try to merge the entities in the
specified file with the content of the server. Note that the "merge"
strategy in most cases will create duplicates of any existing entity.
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.
