Revenj tutorial fixes.

Tutorial changes due to NGS -> Revenj rename.

TODO: pictures currently not updated.
Propagate security exception in ExecuteCommand.

Otherwise it will look as BadRequest
README fix.

Fixed invalid C# code. Fix tab issues.
Domain patterns api change. Templater v1.9.4

Add single event submit in IDataContext.
Version change to v1.0.3
Postgres record null value fix.

It seems that null string was sent as empty string.
While conditions avoided this in most scenarios, it's still incorrect behavoir.
SinglaR2 self hosting.

Using msbuild to compile it.
SignalR watch collection API.

Support for single registration matching collection of provided uris.
Instead of opening a bunch of registrations and connections, use just one.
random changes