--provider on box add supports any format of that provider
VBoxManage customizations can run at different events [GH-1247]
Config validation error if :id in pre-import VBoxManage
Discover and set SSH_AUTH_SOCK on sudo with forward agent [GH-1307]
VirtualBox no longer removes network interfaces [GH-1324]
Mount NFS with UDP protocol by default [GH-1706]
Replace '\' with '/' on synced folders on Windows
Unused config objects are finalized properly [GH-1877]