Create new command extensionapi:listextensions

[Konafets]

This is suppose to be the successor of the current command extensionapi:listinstalled

extensionapi:listextensions: will show all found extensions on the system
extensionapi:listextensions --installed: will only show installed extensions
extensionapi:listextensions --noninstalled: will only show the non installed extensions
extensionapi:listextensions --outdated: Will show extensions which have an update
extensionapi:listextensions --security: Will show extensions with security problems

[ulrikkold]

This would be an awesome update to coreapi.