- improved file structure for _Model_ classes (`app/main/model/..`). Group by database name
- improved database connection handling (fixed persistent DB connections)
- added status information for "WebSocket" installations to `/setup` page (e.g. active connections, startup time)
- removed "ext-zmq" as required PHP extension
- removed "react/zmq" as required Composer package
- removed "websoftwares/monolog-zmq-handler" as required Composer package