Protect all usb writes reads and unplugs with a mutex lock and check libusb release has succeeded before proceeding with a libusb close.
Revert "Protect all usb writes reads and unplugs with a mutex lock and check libusb release has succeeded before proceeding with a libusb close."

This reverts commit beb5f8889de4f5491c831a4bd8824b9c514dbafc.
Only libusb close if libusb release succeeds.
Merge pull request #439 from kanoi/master

Icarus AMU enable the UART
AMU usbstatus correct name from enable UART
Update NEWS for upcoming 3.2.1 release.
Set usbdev in usbutils after checking for nodev to avoid trying to access a dereferenced value.
Extra news.
Bump version to 3.2.1