Added support for building in debug mode (that is compile with -DLW_DEBU...

...G):

    - while running build_makefiles, use "./build_makefiles" to generate
      makefiles for non-debug build and use "./build_makefiles LW_DEBUG" to
      generate makefiles for debug build
    - While running configure, use "./configure" to generate makefiles
      for non-debug build and use "./configure --enable-debug" to generate
      makefiles for debug build
Also did refactoring so that our code now compiles in debug mode.