Feature request: Support Groups

[chriss158]

Hey Walter

Support grouping entities. Maybe in a extra subscreen.
Additional feature could be to show the state of the first entity in the group text, before you enter the group subcreen.

[hufman]

It shows the state of groups (even showing the brightness and color of light_groups as the icon), but I don't have a good way to navigate deeper into a group since the only click handler is used to call the toggle service. If a user wants to view individual entities, they could build a dashboard for more details, but I imagine the main usage pattern will be summary view and toggling.