Add an export script, that excludes unsafe commands from release builds.

[Kubulambula]

I envisioned GDShell as a safe console by default with commands, that should don't do any harm to your projects if a user has access to it. Some commands useful for debugging have to be unsafe to be useful and providing a secondary repository with commands is just annoying to use for both developers and users.

We could make an export script that looks through all available GDShell commands and excludes unsafe scripts by looking at other SAFE flag. It would be a property of GDShellCommand and thus can be overridden in user commands if they wish to exclude their scripts from release builds.