Implement NetworkManager

For now there are two methods:

- `NETWORK:IsUrlAllowed()`: Check whether access to a certain URL is allowed.
- `NETWORK:HttpRequest()`: Perform an HTTP request.

By default access to the network is disabled for all target hosts. It
can be enabled by setting `HttpEnable=1` in the preferences. Individual
hosts have to be added to `HttpAllowHosts` as a comma separated list to
allow access.

See included docs for more details on usage.

extern/IXWebSocket-11.3.2/test/compatibility/python/websockets/Dockerfile

@@ -0,0 +1,17 @@
+FROM python:3.8.0-alpine3.10
+
+RUN pip install websockets
+
+COPY vendor/protocol.py /usr/local/lib/python3.8/site-packages/websockets/protocol.py
+
+COPY *.py /usr/bin/
+COPY entrypoint.sh /usr/bin/
+RUN chmod +x /usr/bin/*.py
+
+RUN mkdir /certs
+COPY *.pem /certs/
+
+WORKDIR /certs
+
+EXPOSE 8765 8766
+CMD ["sh", "/usr/bin/entrypoint.sh"]