gui option to create immutable disk

[isrc]

Hi, As suggested on comment 8 of bug ​http://www.alldomusa.eu.org/ticket/2772 and on several topics on the forum (see ​http://forums.virtualbox.org/viewtopic.php?p=104308#p104308 ), it would be nice to add a GUI option in order to set:

• a disk as immutable or normal
• a snapshot of a immutable disk as autoreset={off|on}

Thanks

[Sorceror]

Duplicate of ticket #2042.