Publish camera uptime.

[bprevost]

I propose that the 'uptime' of the camera is computed and published so that the user can know how long the camera driver has been running. We already have the code available for this and it is available upon request.

[theseankelly]

Sure, I'd take a look at a PR but I'm curious about a couple things -- why is 'uptime' useful to you? When do you publish uptime values (per frame? fixed interval?)?

[bprevost]

Currently we publish uptime as part of a combined message, and uptime refers to the duration of time that the driver has been running. We use this because sometimes the driver loses connection to the camera and we are forced to restart the driver. We have a status screen that monitors all TOF cameras on our network and displays their uptimes as a type of health monitor.

[theseankelly]

Hey @bprevost given the comments on issue #3 is this still a relevant feature?

[bprevost]

We continue to use uptime to monitor the health of our cameras. But it is up to you to determine if this is a useful feature for everyone.