set the default transport to local/null
document how to hide fields (no broadcasts)
Fix transport error handling
Add a way to purge the client/server queue

This is important for testing because spurious and unprocessable (due to
e.g. encoding differences) old messages may clog the queue.
Complain when seeing an unknown meta key
pass NoData and ManyData errors
fixup
error passing
Fix object retrieval.

Large and somewhat intrusive patch.
Extend 'include sub-objects' handling to assocdict

generalize by adding an optional 'include' attribute to the codec
Fix encoding of multiply-referenced objects within other objects

Do this by pre-loading the cache and replacing the original occurrence of
the object with a reference.
Do this for all objects which are not used recursively, i.e. whose
declaration is finished before they're referenced.
Seed the cache in object order, i.e. the object which is completed first
gets added to the cache first.
codec: removed _oi assignment

Instead of setting _oi everywhere and then deleting it afterwards,
remember multiply-referenced locations and set only where necessary.

This also removes the code for optimistic no-reference encoding:
it doesn't have a speed advantage any more.
better debugging
need a session pointer always
better error messages
References to lists were not recorded
export distinct and well-named SQL table meta objects

This is for the client to be able to override the table objects,
so that they can attach their own methods etc.
Cleanup object initialization

Some of these things are their own reference, thus inherit from base and
ref, so the data needs to propagate correctly in __init__
Cleanup (meta) object initialization
Fix error propagation