fix for zgesdd woes

simple configure script checks link option
the sets a CAN_USE variable via sed in header
C++ code #ifdef'ed to hide the unavailable-in-libRlapack zgesdd
updates to dealting with zgesdd
Armadillo patch version 3.930.1

with Conrad's fallback to non-divide-and-conquer, similar to what we tried yesterday
updated configure test accordingly
updated auxlib_meat.hpp
release 0.3.930.1

fix for zgesdd unavailability in Rlapack
updated emacs mode headers for src/*cpp
updated bib entry
Merge pull request #7 from RcppCore/zgesdd_fix

Fix for zgesdd issue, and release 0.3.930.1