Cannot create graph with one quantity using multiquantity sensors.

[x98pl]

If you add a graph to the dashboard that uses data from sensor which provide several quantities, all the data are displayed on one graph. Ther's no possibility to filter them. I.e. I have a BME280 sensor which provide Temperature, Humidity and Pressure. I can add separate blocks for temp, humi or baro using: IDX_n syntax, but using graph_IDX_n syntax for graphs doesn't work. I can use graph_IDX syntax only where all data are shown on one graph, that's unreadable because of scale (baro is around 1000, temperature around 20).

[aalwash]

Fixed in #458