Wildcard entities

[tensiondriven]

Related to #13

HA's native logbook card has support for multiple entities. However, it lacks the ability to select a set of entities based on some attribute, like "All motion sensors" or "input_number.*". (At least not without some jinja-fu).

Having this feature available (showing multiple entities and selecting them by wildcard) would allow us to develop some really nice dashboards.

For anyone interested in picking this up, here's an example of how another contribution implements a syntax for choosing multiple entities: https://github.com/thomasloven/lovelace-auto-entities