MNT: fix duplicate connection event reporting.
ENH: add 'name' attribute to Signal and SignalGroup.


These are essentially keys in the session_manager's dictionary.
User-assigned handles...
ENH: add SessionManager.


In practice used in an IPython session.
Generate a profile via "ipython profile create ophyd".
Modify config file in IPYTHONDIR. See 'example_ipy_conf.py'.
Launch as "ipython --profile=ophyd -i examples/sessmgr.py".
MNT: Scaler class rename to EpicsScaler.