Allow selecting multiple VMs

[dhrdlicka]

This is useful for bulk starting, stopping, resetting or deleting multiple VMs. VirtualBox does support this and they disable menu items for move, clone, settings that trigger a UI when multiple VMs are selected.

[daviunic]

Will be done in version 1.6.

[daviunic]

A problem with this is when you select VMs with different statuses - how to handle the start/stop button etc.

For now, it seems allowing only mass delete is the best option.

[daviunic]

Implemented in 1.6.0 for delete, kill, wipe, open folder and create shortcut operations. More operations might be supported for multiselect in the future.