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

[debrouxl]

I have pushed 6 commits, 3 on the stable "master" branch and 3 additional ones on the testing "master2" branch.
Besides fixes for the aforementioned bugs (and more), there are two new major features (both on the master2 branch, as the code is not final, and I don't have a Prime to test):
* probing support, i.e. the ability to detect which cable and calculator types are available;
* initial support for the Prime emulator (buggy on exit, I need help with the Win32 API, in the area of named pipes and asynchronous I/O), and to a lesser extent, the 39gII emulator (last tested before I implemented probing support)

Windows users will find the latter capability moderately useful, Linux & MacOS X users could find it more useful - maybe the most direct use for that feature in the short term shall be my own testing for changes to the upper layers from Linux, through Wine.
In fact, the "send chat" and "recv chat" operations were implemented thanks to an earlier version of the emulator support, before I experienced significant trouble making large packet support work (on the reading side).
Due to my inability to close / flush the connection correctly, for now, the emulator needs to be restarted after test_hpcalcs exits.

I have updated the Windows binaries (see http://www.hpmuseum.org/forum/thread-52-...tml#pid176 for download links) with the probing and emulator support.
Beware that I might have broken support for real Prime calculators in the process, so if you want a dependable program, stick to the master branch and an earlier version of the Windows binaries

As usual, bug reports and code contributions from Windows developers are more than welcome.
Thanks in advance