added beatification
beginning repair of command_queue and associated
test. The preferred way of instantiating entities
with the create class method is used.

Start of moving away from storing the entity type
from .type to .entityType.

Entity class reference on entityDef is now stored
as ._entityClass rather than .Entity
added a default sync, which does nothing.

refactored command_queue somewhat. Removes Step usage
in favour of async. Commands can be executed without
blocking.
more type -> entityType conversion.
fixed most command_queue tests
added a serial execution flag for the command queue
which means that commands can block other commands
until they are finished.
updated README.md