Add support for Lexus

[joro75]

The mytoyota library now also has support to retrieve the information from cars from Lexus.
Please extend the domoticz plugin to also support Lexus cars.
Proposal is to add an additional dropdown box, where the car manufacturer can be selected: Toyota / Lexus.

And additional improvement can be to also add an 'Auto' option to the dropdown box. This would first trying 'Toyota', and if that isn't working can try 'Lexus'. The working car manufacturer can then be cached and reused in subsequent calls.

Also should update the icon to show the Lexus icon, and include references to the app on the Lexus websites.