Add a generic graph page for temperature graphs

[galadril]

Like how its implemented in domoticz:

[galadril]

Example api endpoints to get the data: /json.htm?type=graph&sensor=temp&idx=12&range=2020-07-29T2020-08-05&graphtype=1&graphTemp=true&graphChill=false&graphHum=false&graphBaro=false&graphDew=false&graphSet=false

[galadril]

Here are some first results/screens:

New icon in action bar for the graphs

Choose your devices for the graph

Choose the type of graph values

Result graph

You can also set a different date range

[galadril]

The result: