libhpcalcs: portable (Windows / MacOS X / Linux) connectivity kit library

[debrouxl]

Thanks
Diffing the output files shows that the two failures are identical, the two successes are identical, and the only difference between a failure and a success is that upon failure, the calculator replies nothing (no error code, for instance - the DBUS, DUSB and NSP protocols of the TI-Z80 series, TI-68k series and Nspire series have that), instead of a ready packet.

I won't be able to do much about it, only slightly reworking the code for checking whether the calculator sent back a "ready" packet (which could now be termed "ready / success", I guess), and return a special error code indicating transfer error if no such packet was returned to the computer before timeout. Currently, "ready" packets are swallowed.
If something in the USB HID stack (or the calculator side ??) cannot cope with more than several dozens of KBs of host -> device data, and silently discards or corrupts data, well...