This refactors `Discover.connect_single` by moving device instance construction into a separate device factory module.
New `SmartDevice.connect(host, *, port, timeout, credentials, device_type)` class method replaces the functionality of `connect_single`,
and also now allows constructing device instances without relying on UDP discovery for type discovery if `device_type` parameter is set.
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Co-authored-by: Teemu R. <tpr@iki.fi>
* Add a note about socket sharing
* Show inherited members for apidocs
* Remove outdated note of emeters not being supported on smartstrips
* Describe emeter and usage modules, add note about NTP for time sync
* Describe lib design and modules
* Bump sphinx version, ignore d001 (line-length) for doc8
* demote energy & usage to 3rd level, promote api for 2nd
