Online-monitor

This release brings two new features

- A `plugin_online_monitor` script, allowing to add paths to the `online_monitor` default search paths. Usage:


plugin_online_monitor my/custom/online_monitor/plugin/path

or

cd my/custom/online_monitor/plugin/path
plugin_online_monitor

- A producer sim `silab_default_producer`, located under the [examples](online_monitor/examples/producer_sim), has been added and is automatically available. It runs out of the box for most SiLab-type DAQ outputs and can be used in the configuration.yaml like:


producer_sim:
DAQ:
kind: silab_default_producer
data_file: path/to/my/data.h5
backend: tcp://127.0.0.1:5500
delay: 0.2

This version fixes the installation of `online_monitor` via the Python Package Index.
Run

pip install online-monitor

to install the package from there

See 18! Highlights

- Dropping Python 2 support -> Only Python >= 3.7 supported from here on
- Moving CI (Linux / Windows) to GH actions
- Drop deprecated `nose`, use `pytest` instead
- Fixing the package:
- Remove use of deprecated use of `QtGui`/ `Qt` through `pyqtgraph`, use `pyqt5.QtWidgets` instead
- Fix versions to match [`pyqtgraphs testing matrix`](https://github.com/pyqtgraph/pyqtgraph#qt-bindings-test-matrix)
- Fix `DeprecationWarnings` due to `configparser.SafeConfigParser` -> `configparser.ConfigParser`
- Fix tests / coverage

- Fixing Python 2.7 and 3 compatibility issues (changes in the dict implementation)
- Fixing installation issues when using pip and the online_monitor package is not yet available.

Some quirks with serialization are fixed by using the json api provided by pyzmq (15). Unit tests are added for 3 different ways to serialize data with numpy arrays.

Not backward compatible API change to fix typo: serialze -> serialize

Enhancements:
- With newer pyzmq releases it was observed that the HWM feature at the receiver side does not work anymore and the online_monitor does not stay real-time. The reason for this was not found and the documentation and forums are not helpful. Therefore a input FIFO is added to the transceiver module to be in charge of data dropping.

- Data dropping is now not determined any more by CPU utilization but by input FIFO size. Each entry in this FIFO is one received data chunk. The config option is max_buffer in the yaml file.

- stop_online_monitor terminal command that kills all instances of producers, converters and reveives. This is useful when developing and crashes are expected.