12.6 : New event sources and solve bugs on evaluation of attributes and alarms

Changes in submodules:

Arrays: 
  Solve bug in CSVArray.getAsTree when lastbranch is a column name
  Apply x/y offsets on calls to CSVArray.resize()
  Add try/except to CSVArray.set()

Callbacks/EventSource:
  Adapted to multiple sources, add dummy for persistence
  Rethrow exceptions on EventSource/CachedProxy.read(_raise=True) (default)
  Solve EventSource filtering and polling bugs, cleanup now() references
  solve issues with poll-only  attributes, tune for >1000 events/second
  Add write_with_read argument to EventSource.init()
  Enable EventSource subscribe without listeners
  Enable EventSource.removeListener(sequence)
  Add extra counters to EventSource, solve bug in Cached values

Dev4Tango:
  add LastUpdate and MemUsage attributes to all devices

Dicts:
  ThreadDict: add _updates refresh on write hardware 

Functional
  Add iif(condition,truepart,falsepart,foward)

FolderDS/GUI:
  add SaveFolder attribute
  Solve bug in FolderGUI.ListFiles

Qt: 
  Adapt fadango.QEvaluator to latest PyQt4
  patch for taurus 4
  Solve problems with non-string models in QSignalHook

Scripts:
  Add offset to tango2csv.add_properties_to_csv()
  Enable host argument to tango_servers start/status/stop
  Use tango_property to export DynamicDS properties

Tango:
  Remove domain info in get_tango_host() (pytango bug)
  Adapt get_device_info to multihost
  Adapt fakeAttributeValue to taurus4
  Solve bug in TangoEval formula starting with 'not '
  add get_server_property method
  check_attribute to allow proxy or taurusattribute as argument

Tests/simulation: 
  Set SimulatorDS as default simulation class

Threading:
  Add ThreadedObject.get_avg_delay method