Add typescript declaration, also publish as module

package.json

@@ -10,7 +10,9 @@
     "type": "git",
     "url": "https://code.treora.com/gerben/document-outerhtml"
   },
-  "main": "lib",
+  "main": "lib/index.js",
+  "module": "src/index.js",
+  "types": "src/index.d.ts",
   "scripts": {
     "build": "babel -d lib src",
     "postpublish": "publish-to-git --force",
@@ -20,7 +22,8 @@
   "author": "Gerben <gerben@treora.com>",
   "license": "CC0-1.0",
   "files": [
-    "lib"
+    "lib",
+    "src"
   ],
   "devDependencies": {
     "ava": "^1.4.1",
@@ -41,6 +44,6 @@
     ]
   },
   "dependencies": {
-    "doctype-to-string": "git+https://code.treora.com/gerben/doctype-to-string#semver:^0.1.3"
+    "doctype-to-string": "git+https://code.treora.com/gerben/doctype-to-string#semver:^0.1.4"
   }
 }

src/index.d.ts

@@ -0,0 +1,3 @@
+declare module 'document-outerhtml' {
+    export default function(doc: Document): string
+}