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

[debrouxl]

I pulled Daniel's 5 commits into my master branch, then I pushed the tentative support for .hpappnote and .hpappprgm files made in 2013 but never confirmed or infirmed by anyone (AFAICT).
The master2 branch has been force updated with the more experimental commits for which I posted a tarball in my previous post.

Thanks again Daniel