Fixed XML documentation error.
Applies new configuration settings only if they are different from current one.
Fixed AssemblyVersionUpdate.cs entry in .gitignore.
Fixed bug in applying configuration setting

NullReferenceException caused by not updating current connection setting
variable if new connection setting is the same as the current one.
Reorganised ExtensionMethods class

Sorted methods and added XML documentation.
Fixed changed method names  from previous commit.

Previous commit: bf59f7075820c59a84f056deef19b587bc5348b5
Changed method name: IsNullOrBlank(str) => IsNullOrEmpty(str)
Single Instance mode added

Runs in single instance if the 'singleprocess' flag is specified or a
debugger is attached to the process.