Expose libusb_get_version in usb1 module.

Also, fix its prototype declaration.
Do not use deprecated class in tests.
Expose iterator API to walk configurations.

Also, fix a typo in "USBDevice.iterConfiguations" name.
Document more classes & methods.
Fix python3 compatibility.
Fix USBDeviceHandle.getStringDescriptor .

Also, document locales.windows_locale as a way to get readable language
code representation.