Temperature Monitors may report null values as temperatures,
thus special handling is needed. This commit also reworks
temperature store updates to use the subscription cache
rather than perform its own caching of "last temps".
Signed-off-by: Eric Callahan <arksine.code@gmail.com>
This callback will only fire after a component has requested
a subscription, preventing early updates while the component
is waiting for the subscription request to complete. It is still
valid for components to register the "server:status_update"
event handler if this behavior is not a concern.
Signed-off-by: Eric Callahan <arksine.code@gmail.com>
