Shorted node type names.
Optimize js not to cause jsPlumb work on every update.

Only position updates really require jsPlumb to be aware of
node updates. Change to detecting whether the position actually
changed and only notify jsPlumb in those cases. This prevents
the GUI from getting stuck from relatively modest update work.
Lots of potential left but fast enough for now.
Introduce TickingFlow trait for source with frequency.

Provides a editable "freq" property which sets the frequency in
Hz for receiving a Tick message on the object. Removes code
duplication between NumberSource and IpsumSource.
Introduce configuration update rate limiting.

Not exactly matching the description but still fixes #11 .
The rate limiting prevents the flow network from flooding
the network with configuration updates killing the
responsiveness of the app by overloading the network and the
client browser.

With this patch configuration updates above 4 per second are
discarded. As this in theory might lead to important configuration
updates being lost updates created in reaction to outside
configuration changes aren't limited.
Introduce FlowTrace sink

Part of #10. Element which displays a table of
n (by default 5) previously received messages in a
table inside the element.

The js has special behavior for this element
dependent on the NodeType. In theory this could
easily be generalized but this would probably not
be worth the work right now.