Improvements for decentralized

[MarcusZuber]

Here I collect improvements that would be beneficial for the decentralized experiment control, that will be implemented in the future.

• Timeouts for the zmq-streams (@tfarago, needs also changes in uca-net)
• Since the addons now know the experiment instance the OnlineReco can extract most of the parameters from the experiment (num_projections, angular_range,...) Could be done with Adds qt-like signals to Parameters #548
• I implemented factories for the different experiment types (at ~80% finished)
• Test should instantiate each (dummy) device and check if all parameters are at least readable.
• Parameterizable.info_table should set value to NA for all exceptions.
• Implement "RemoteReader"
• All parameters for Tango-servers (remote walker, reco, etc.) should be always read from the device server and not cached in concert.
• The json-logging in the experiment should ask the devices in parallel (we have some really slow devices...)
• Make "endpoint" more consistent. Sometimes a string-description is used, somethimes the ComData object.
• Add integration tests with tango-database
• The reco-tango-server should pass all reco-args (maybe as a pipe). This allows to get rid of tofu as a requirement on the non-reconstructing concert
• Add a generic remote ufo addon, where I can define the graph (maybe with a json description).
• We could make the endpoint writer and not walker specific. Then, one remotewalker would be sufficent, where arbitrary addons could connect to.
• Possibility to delete chached projections in remote-online-reco (I have multiple instances running for different tasks and at some point the full memory is used, so I want to free the "unused" ones)
• In concert.ext.tangoservers.reco setup arguments without the "exec(setter/getter_string)"
• Re-think exception-propagation (currently an error in the online-reco kills the whole experiments after a few frames. Maybe we should finish it first and then raise the exception? Maybe we could make this a flag in the addon, if it should trigger a experiment stop)
• Allow (again) 3D volumes to be shown by the pyqtgraph-viewer Improvements of PyQtGraphViewer #547