Pcaspy

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* Fixed that alarm and warn limits are taken from *lolo*/*hihi* and *low*/*high* fields. (Issue 11).
* Fixed `example/alarm_severity.py` so that `MTEST:STATUS` and `MTEST:RAND` are writable.

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* Fixed that cas.py is not installed (Issue 10).
* Fixed that put callback may fail if driver invokes :meth:`Driver.callbackPV` too soon(Issue 9). Thanks to Kay Kasemir.
* Added 16bit short integer type.
* Added printout of exceptions that are raised inside Python code.
* Added :meth:`Driver.setParamEnums` to change the states of enumerate PV at runtime (Issue 4).
* Added basic logging support. To enable console logging::

logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(name)s: %(message)s')

* Changed so that timestamp is updated whenever :meth:`Driver.setParam` is called.
It was only updated when the values are new. The new behavior is the same as EPICS IOC.
* Packaging changes:
* Binary packages are distributed through `PyPI <https://pypi.python.org/pypi/pcaspy>`_.
* Document is hosted at `Read the Docs <https://pcaspy.readthedocs.org>`_.

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* Fixed PV initial status. By startup, it is UDF/INVALID.
* :meth:`Driver.setParam` makes a copy of list/numpy.ndarray objects.
This solves the racing condition, in which the value could be in the middle of updating
while CA client reads the value. Thanks to Kay Kasemir.

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* Change from GPL to New BSD License for broader audience.
* Added __version__ info
* Added access security control
access security control file can be loaded using :meth:`SimpleServer.initAccessSecurityFile`.
The loaded rules can then be assigned to PV's *asg* field.
`example/access_control.py` provides an example and better explained in :ref:`tutorial-access-security-control`.

* Added new type char.
It is used to represent a long string (>40 chars). And it behaves just like string parameters in driver.
example/pysh.py provides a concrete example, in PV `COMMAND` and `OUTPUT`.

* Added timestamp info.
The timestamp is set at each setParam call with new value different to current value.

* Added alarm/severity info.
* For *enum* type PV, the severity is configured by its *states* field.
It is a list of severity states, which can be NO_ALARM, MINOR_ALARM, MAJOR_ALARM, INVALID_ALARM.
If current state's severity is other than NO_ALARM, alarm is STATE_ALARM.
* For *int* or *float* type PV, the alarm state is configured by its *low*, *high*, *lolo*, *hihi* fields,
in analogue to EPICS database.
* `example/alarm_severity` provides an example.

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* Fixed gdd vector memory leak introduced in 0.2
* Added casPV's writeNotify method for EPICS base 3.14.11+
* Release GIL for each C function call
* Added tools.ServerThread running server process in separate thread
* Added preliminary Qt GUI integration example using tools.ServerThread

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* Added Python 3 support
* Added numpy data types support
* Fixed the driver registration issue.
* Rework gdd put/get methods
* Added gdd unittest cases
* Remove Makefile in favor of setup.py