fix: enable arm buttons based on supported alarm features

[rchl]

Resolves #365

[rchl]

@akloeckner Care to review?

[akloeckner]

Sure! I'll be able to test earliest Thursday, though...

[akloeckner]

Actually, my manual alarm panel supports all those features. So, not much to test in the end. Looks good!

If we were to clean up while passing by, I'd fix up the isDisarmed function to simply

return entity.state != 'disarmed';

[rchl]

Removed isDisarmed. It doesn't add much and I would prefer to have as few scope methods as possible.

[akloeckner]

👍 My parameter for a good PR also is "more lines removed than added". ;-)

Just a logical twist, that strikes my mind: Is it really correct to enable the arm actions only, if the alarm is already armed. (And vice versa.) It seems to work correctly, but I don't understand, why...

[rchl]

No, you are right. It's backwards and doesn't work as intended. Will fix.

[akloeckner]

I hope you weren't waiting for my approval...

[rchl]

Was planning to merge eventually but was not in a rush. :)