add typegen for 2.7

package.json

@@ -30,7 +30,12 @@
   "main": "build/LineUpJS.js",
   "unpkg": "build/LineUpJS.js",
   "module": "src/index.js",
-  "types": "src/index.d.ts",
+  "types": "build/types/2.7/index.d.ts",
+  "typesVersions": {
+    ">=3.1": {
+      "*": ["src/*"]
+    }
+  },
   "sideEffects": [
     "*.scss",
     "*.css"
@@ -68,7 +73,8 @@
     "dev": "npm run clean && npm run compile:dev && npm run build:dev",
     "watch": "webpack --mode development --watch --devtool source-map",
     "start": "webpack-dev-server --mode development --devtool source-map",
-    "predist": "npm run build",
+    "types:27": "cd typeGen/ts27 && npm i && npm run compile",
+    "predist": "npm run build && npm run types:27",
     "dist": "mkdirp dist && cross-zip ./build ./dist/lineupjs.zip",
     "postdist": "npm run docs && cross-zip ./build/docs ../dist/lineupjs_docs.zip",
     "preversion": "npm test",

typeGen/ts27/package.json

@@ -0,0 +1,8 @@
+{
+  "devDependencies": {
+    "typescript": "~2.7.2"
+  },
+  "scripts": {
+    "compile": "tsc -p ."
+  }
+}

typeGen/ts27/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "emitDeclarationOnly": true,
+    "declarationDir": "../../build/types/2.7/",
+    "skipDefaultLibCheck": true,
+    "skipLibCheck": true
+  }
+}