* Add new SessionData collection to store user session data available to
server and client
* Limit the Users fields sent to the client by `myCards`, `dueCards`,
`brokenCards`, and `globalSearch` using new `Users.safeFields`
* clean-up
* use @ and # as the abbrevs for the user and list operators
* comment out debug code
* Modify display of card result counts
* Fix bug with publication not returning current user document
* Add translation tags
* Use translation tags for showing result count
* Add logic for selecting cards by labels
* Readd code for searching card text that was mistakenly deleted