Add getOptionalConnection.
Merge pull request #123 from csmith/master

Tidying and deprecation fixes.
Merge pull request #124 from greboid/optional-connection

Add getOptionalConnection.
Add MutableAutoCommand.
Merge pull request #125 from greboid/auto-command-models

Add MutableAutoCommand.
Some OptionalConnection work.

Deprecate getConnection, fix CustomWindow's getOptionalConnection
returning null, change a couple of usages.