more internal rearchitecturing

package.json

@@ -6,7 +6,8 @@
   "homepage": "https://6to5.org/",
   "repository": "6to5/6to5",
   "preferGlobal": true,
-  "main": "lib/6to5/index.js",
+  "main": "lib/6to5/api/node.js",
+  "browser": "lib/6to5/api/browser.js",
   "bin": {
     "6to5": "./bin/6to5/index.js",
     "6to5-minify": "./bin/6to5-minify",
@@ -14,8 +15,7 @@
     "6to5-runtime": "./bin/6to5-runtime"
   },
   "browser": {
-    "./lib/6to5/index.js": "./lib/6to5/browser.js",
-    "./lib/6to5/register.js": "./lib/6to5/register-browser.js"
+    "./lib/6to5/api/register/node.js": "./lib/6to5/api/register/browser.js"
   },
   "keywords": [
     "harmony",