Adjustments to WAsm file system layout and compilation options

Moves the full.sysout from the root of tle system to /medley/loadups/full.sysout,
adds /medley/lispusers/BACKGROUND-YIELD.LCOM and an Emscripten/WAsm specific
site init file at /usr/local/lde/site-init.lisp

Adjusts options so that the options are in the correct place for the
compiler and loader.

src/lde.html

@@ -11,7 +11,7 @@
     </div>
     <script type="text/javascript">
       var Module = {
-          arguments: ["full.sysout"],
+          arguments: ["medley/loadups/full.sysout"],
           canvas: (function() { return document.getElementById('canvas'); })()
       };
     </script>