VM SUP startup log creation

[Mihai Hanor]

VirtualBox creates VM shortcuts without adding the --sup-startup-log command line parameter. A VM receives the --sup-startup-log parameter only when it is started from the VirtualBox Manager. Most users will not be aware of this and they will provide whatever log resides in the VM folder. Maybe it should be better to use a per VM property, that defaults to enabled. An example of such a situation can be found here.