I've moved the D Language Specification files into their own spec/ subdirectory in order to clean up the source tree a bit and ease future work in compiling the specification into EPUB. To this end, I have also updated the win32.mak and posix.mak files to accommodate these changes. I've done some simple testing with the posix.mak file but almost none on the win32.mak file. I can't think that I've broken anything.