refactor: simplify retrieval of 3-party scripts dependencies

- keep them in their own module directories
- find their path with require.resolve()

package.json

@@ -37,7 +37,7 @@
     "npm": ">=4",
     "yarn": ">= 0.20"
   },
-  "main": "src/index.js",
+  "main": "dist/index.js",
   "bin": {
     "ace": "dist/cli/cli.js"
   },
@@ -79,9 +79,7 @@
     "start": "node dist/cli/cli.js",
     "clean": "rimraf dist && mkdir dist",
     "prebuild": "yarn run clean -s",
-    "build": "yarn run build:js -s && yarn run build:axe -s && yarn run build:h5o -s",
-    "build:axe": "mkdir -p dist/ext/axe && cp node_modules/axe-core/axe.min.js dist/ext/axe/",
-    "build:h5o": "mkdir dist/ext/h5o && cp node_modules/h5o/dist/outliner.min.js dist/ext/h5o/",
+    "build": "yarn run build:js -s",
     "build:js": "cp -R src/ dist",
     "build:watch": "watch 'yarn run build' src",
     "test": "echo add tests",

src/checker/checker-nightmare.js

@@ -7,13 +7,13 @@ const report = require('../report/report.js');
 const axe2ace = require('../report/axe2ace.js');
 const winston = require('winston');
 
-const PATH_TO_AXE = path.join(__dirname, '../ext/axe/axe.min.js');
+const PATH_TO_AXE = path.join(path.dirname(require.resolve('axe-core')), 'axe.min.js');
 if (!fs.existsSync(PATH_TO_AXE)) {
   winston.verbose(PATH_TO_AXE);
   process.exit(1);
 }
 
-const PATH_TO_H5O = path.join(__dirname, '../ext/h5o/outliner.min.js');
+const PATH_TO_H5O = path.join(path.dirname(require.resolve('h5o')), 'dist/outliner.min.js');
 if (!fs.existsSync(PATH_TO_H5O)) {
   winston.verbose(PATH_TO_H5O);
   process.exit(1);