Added support for USB on Linux.
* DiscImageChef/Commands/DeviceInfo.cs:
* DiscImageChef.Devices/Device/Variables.cs:
Added support for USB detection and metadata.
* DiscImageChef.Devices/Linux/Extern.cs:
* DiscImageChef.Devices/Linux/Command.cs:
Added readlink(3) support, for getting symlink destinations.
* DiscImageChef/Options.cs:
* DiscImageChef/DiscImageChef.csproj:
* DiscImageChef/Commands/DeviceInfo.cs:
Added "device-info" command.
* DiscImageChef.Decoders/SCSI.cs:
Correct size miscalculation.
Do not print "Device claims no standard", generates too much
noise.
* DiscImageChef.Devices/Device/Constructor.cs:
Add OS error detection and handling.
On Linux move to opening O_RDONLY and O_NONBLOCK to allow
opening read-only media and removable drives without media.
* DiscImageChef.Devices/Device/Variables.cs:
* DiscImageChef.Devices/Device/ScsiCommands.cs:
Add OS error detection and handling.
* DiscImageChef.Devices/DiscImageChef.Devices.csproj:
* DiscImageChef.Interop/DiscImageChef.Interop.csproj:
Downgraded .NET version.