cython interface to hidapi

 This has been tested with:
 .
 * the PIC18F4550 on the development board from CCS with their example program.
 * the Fine Offset WH3081 Weather Station.
 .
 It works on Linux, Windows XP and OS X.
 .
 HIDAPI is a multi-platform library which allows an application to interface
 with USB and Bluetooth HID-Class devices on Windows, Linux, FreeBSD, and Mac
 OS X. HIDAPI can be either built as a shared library (.so or .dll) or
 can be embedded directly into a target application by adding a single source
 file (per platform) and a single header.