Merge branch 'master' into feature/wiener
Documenting breifly what's the Wiener Attack about.

Enounce Wiener's theorem, more or less how it's written on twnty years; using
doxyigen style.
Creating qarith.c, as module for arithmetic operations with bignums.

Moving some code from wiener's attack inro qarith, in order to provide easy
access to square root operations also for other attacks.
Doing this, I also moved the unittests for this function to test_qarith.c, and
added it to Makefile.am as test target.
Test test_qa_sock.c

NO idea how it disappeared from the tree, or whether it haz ever been there.
Merge branch 'feature/wiener' into fix/posix
make check available also for test_qa and test_qa_sock.

Something strange, test_qa is failing here. Checking later.