Beginning to separate out SDP utilities

--HG--
rename : examples/lapack-like/LogDetDivergence.cpp => examples/convex/LogDetDivergence.cpp
rename : include/elemental/lapack-like/LogBarrier.hpp => include/elemental/convex/LogBarrier.hpp
rename : include/elemental/lapack-like/LogDetDivergence.hpp => include/elemental/convex/LogDetDivergence.hpp