Create (user) sessions

[roquelopez]

Currently, if two or more users are using the hololens or replaying a video through the API at the same time, the streams get mixed. Modules that read data streams, like reasoning or perception, are the most affected when more than one user are generating data.

It would be great if the API and Dashboard can handle multiple sessions.

Last week (before the demo), I had to being checking if nobody was using the API, to make my own tests. From here to November, more users will be using the API. So, this new feature will be very useful to avoid waiting times to use the API.

@hvo @beasteers @soniacq