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

[debrouxl]

Thanks for making a detailed install procedure
With your permission, I'm simply going to adopt it for the README, with at least the following tweaks:
* in step 1, use the union of the package list mentioned in install_hplp.sh and your list;
* in step 3, use install_hplp.sh instead of manual cloning, configuring with wrong CFLAGS, and manual makefile edit

And thanks for the bug report and patch.

Cristian: the most common cause of this error is that LD_LIBRARY_PATH does not contain the folder where the shared object is. You need to add /usr/local/lib to LD_LIBRARY_PATH, or use --prefix=/usr when configuring hidapi.