Add submodules for most of the deps
Don't create a global 'clipboard' object in the clipboard module
Remove in-repo copy of lua 5.1 and use the submodule instead
Build Lua as C

Linux distros nearly always package Lua built as C, so build it as C on
Windows as well to cut down on needless differences.
Remove most of the fetched dependencies since they're now submodules
Add the beginnings of a README file