Pyvlx

Fixed bug of not having correct position set when interrupting a movement.

Pyvlx may now control ON_OFF_SWITCHes. They are loaded as node and may be controlled via:

`await pyvlx.nodes['CoffeeMaker'].set_on()`

or

`await pyvlx.nodes['CoffeeMaker'].set_off()`

* Improved position handling / processing.
* Enums for Originator, Priority and Velocity.
* Processing incoming FrameNodeStatePositionChangedNotification frames.
* New update callbacks when nodes are updated.
* Improved unit tests.

* Correct implementation of AliasArray
* Correct parsing of timestamps
* Transmit UTC time to gateweay via GW_SET_UTC_REQ
* Enable House Monitor via GW_HOUSE_STATUS_MONITOR_ENABLE_REQ
* Correct parsing of GW_NODE_STATE_POSITION_CHANGED_NTF
* Code cleanup (e.g. using isort)

* Added heartbeat module for sending get state request to api every minute to keep connection alive.
* Moved all frames to separate module.

Description
-----------

Progressing with complete reimplementation of new KLF 200 API

Highlights
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* Load Node information from API
* Set position of Nodes (esp. windows, rollershutters, blinds)
* Rename nodes.
* Retrieve Version information from gateway
* Better handling of lost connections, automatic reconnect.