* async++, small powerstrip improvements
* use asyncclick instead of click, allows defining the commands with async def to avoid manual eventloop/asyncio.run handling
* improve powerstrip support:
* new powerstrip api: turn_{on,off}_by_{name,index} methods
* cli: fix on/off for powerstrip using the new apis
* add missing update()s for cli's hsv, led, temperature (fixes#43)
* prettyprint the received payloads when debug mode in use
* cli: debug mode can be activated now with '-d'
* update requirements_test.txt
* remove outdated click-datetime, replace click with asyncclick
* debug is a flag
* make smartstripplug to inherit the sysinfo from its parent, allows for simple access of general plug properties
* proper bound checking for index accesses, allow controlling the plug at index 0
* remove the mess of turn_{on,off}_by_{name,index}, get_plug_by_{name,index} are enough.
* adapt cli to use that
* allow changing the alias per index
* use f-strings consistently everywhere in the cli
* add tests for get_plug_by_{index,name}
