Added RunOnWebSockets and RunOnSessions methods to run user procedures on WebSockets and sessions with some filters.
Merge branch 'develop' of https://github.com/Starcounter/Starcounter into develop
Added code that sets Current WebSocket and Session.
Added error code for SQL.
Merge branch 'develop' into issue/1754

Conflicts:
	src/Starcounter.XSON/Sessions/Session.cs
.