Update CI to cppTango 9.4.1, change default ORBendpoint host to 0.0.0.0, fix tests

Multiple small changes in preparation for release:

Update to cppTango 9.4.1 for CI

• For AppVeyor, we are using libtango_9.4.1_v141_x86_static_release.zip and libtango_9.4.1_v141_x64_static_release.zip
• The pytango-builder v1.2.0 container images are built with cppTango 9.4.1. They also have libzmq updated from 4.2.0 to 4.3.4. These images will be used for binary wheels.

Change default ORBendpoint host to 0.0.0.0, and for tests use 127.0.0.1

• cppTango 9.4.1 does not support an empty host field in the command line options like -ORBendpoint giop:tcp:<host>:<port>. Use 0.0.0.0 as the default instead. See cppTango#1055 (closed).
• Specify host for TangoTest cmd in test_client.py as 127.0.0.1 instead of empty string.
• Changing the TangoTest host required better detection of the port the process is listening on for CORBA connections.

Minor

• Added missing packaging dependency in README and AppVeyor
• Fixed deprecation of distuils.version.LooseVersion - now using packaging.version.Version instead.
• Change event tests to use host 127.0.0.1, and ephemeral port.

Fix AppVeyor tests - numpy.dtype(int) check under Windows

• AppVeyor was failing the empty spectrum tests specifically with type int. The problem is the different interpretation of numpy.dytpe(int) on Windows (int32), and Linux/macOS (int64). Use some existing type lookup tables to get numpy.dtype('int64') on all platforms.

More details about all of these changes are given in the commit messages.