Additional improvement to CommonJS Modules support

Now implements (and mostly follows) requirements of Modules/1.1 spec
  implementes only the required "secure sandbox" subset of the spec
  `module` free variable changed from the `moduleInfo` to an id container
  `require` free variable given a "main" property
  boot module scope closed and exported
    this also changes the interface between boot and bootprefix slightly
    (should now be able to create multiple TW instances under node)
 BREAKING CHANGES:
  The tiddlywiki module itself now exports a single constructor function
  Modules which depended on `module` referring to `moduleInfo` will break
  Modules which don't conform to Modules/1.1 will break
    (by attempting to modify require.main or module.id)

tiddlywiki.js

@@ -4,7 +4,7 @@
 This is invoked as a shell script by NPM when the `tiddlywiki` command is typed
 */
 
-var $tw = require("./boot/boot.js").$tw;
+var $tw = require("./boot/boot.js").TiddlyWiki();
 
 // Pass the command line arguments to the boot kernel
 $tw.boot.argv = Array.prototype.slice.call(process.argv,2);