Updated:
   README.md:  describes process of building/using DLL
   makelibzmq: Build DLL as well as static library (unless BUILD_DLL=false)
   maketests:  Dynamically link to ../src/libzmq.so if present
   runtests:   Explicitly place ../src at start of LIBPATH
   makeclean:  Also remove files created for DLL
   cxxall:     Bumped updated date to reflect last edit