* Added scan_length to AddressableScanEffect (allow more than one LED)
* Added check for scan length being longer than addressable light
* Added config option 'scan_length' to AddressableScanEffect (default: 1)
* Renamed scan_length to scan_width, removed erroneous length check
* Fixed indentation issue in addressable_light_effect.h
Co-Authored-By: Otto Winter <otto@otto-winter.com>