Manage multiple Netatmo User accounts (and OAuth credentials)

The main change lies in parsing the openhab.cfg file differently. One can simply add the needed parameters like this

netatmo:clientid=54329b841e7759579d88csdsdlkfj
netatmo:clientsecret=W5TMX84o8KJHCX/&5WILmOq5r28AIyjdqDZuqnetsjku
netatmo:refreshtoken=54328ae62077593f867ab438sdvi8addede2c19fb73b61e634f98ef4a2063

or additionally add an user id to which this credentials belong to like:

netatmo:thomas.clientid=54329b841e7759579d88csdsdlkfj
netatmo:thomas.clientsecret=W5TMX84o8KJHCX/&5WILmOq5r28AIyjdqDZuqnetsjku
netatmo:thomas.refreshtoken=54328ae62077593f867ab438sdvi8addede2c19fb73b61e634f98ef4a2063

netatmo:peter.clientid=54329b841e7759579d88csdsdlkfj
netatmo:peter.clientsecret=W5TMX84o8KJHCX/&5WILmOq5r28AIyjdqDZuqnetsjku
netatmo:peter.refreshtoken=54328ae62077593f867ab438sdvi8addede2c19fb73b61e634f98ef4a2063

Best, Thomas E.-E.