This is what POSIX seems to specify, and also what glibc getopt does.
We were already borrowing a getopt() from the BSD family until the day we write our own. This patch borrows a slightly more modern one so we also get getopt_long(). Fixes #190. See also #91 for the desire to eventually NIH our own getopt()..
Things were getting a little crowded in the project root, so this patch moves the Lib*/ directories into Libraries/.