Crossbar

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* fix: subscription forwarding (1915)
* fix: RLink fixes (1913)
* fix: make standalone the default personality (1900)
* new: implement dynamic node key (1906)
* fix: Python 3.10 compatibility issues (1897)
* fix: add systemd-notify support to docs (1883)
* fix: assign authid to router components to work with rlinks (1893)
* fix: install from source (1884)
* new: depend on Autobahn v21.11.1
* new: expand WAP web service (1878)
* fix: various adjustments and fixes after integration of FX code base
* new: open-source code for "Crossbar.io" (~26k LOC), incl. router-to-router links
* new: changed license from AGPLv3 to [EUPLv1.2](https://eupl.eu/1.2/en) (under IP ownership of Crossbar.io Technologies GmbH)

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* fix: depend on hotfix in Autobahn for Twisted v21.2.0 (see: https://github.com/crossbario/autobahn-python/issues/1470)

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* new: minimum supported Python version now is 3.7
* new: output more version infos on "crossbar(fx) version"
* fix: pin to pip v19.3.1 because of "new resolver" and confluent dependencies with conflicts
* fix: do _not_ use wsaccel on PyPy (the JIT is faster)
* fix: Docker image baking scripts and CI automation for PyPy 3

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* new: callback user component function "check_config" on container/router components
* fix: support Docker images for ARM (32 bit and 64 bit)
* fix: bake Docker multi-arch images
* fix: PyPy3 CI
* new: enable autobahn client unit tests

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* fix: update and migrate CI/CD pipeline to GitHub issues
* fix: depend on Autobahn v20.12.3 - this fixes a potential security issue when enabling the Web status page (`enable_webstatus`) on WebSocket-WAMP listening transports-

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* fix: depend on Autobahn v20.12.2
* fix: CI/CD - disable MacOS CI, update Docker imaging scripts