add @mocha/markdownlint-cli; closes #3172

- forked [markdownlint-cli](https://npm.im/markdownlint-cli) to fix a
  glob-related bug; will abandon our version if/when it's merged
- add `.markdownlint.json` config
- remove "allow trailing spaces" for Markdown in `.editorconfig`
- add to `lint` target & create `markdownlint` script in `package.json`,
  which is dumb, but we're stuck with it for now

.editorconfig

@@ -13,6 +13,3 @@ indent_size = 2
 
 [Makefile]
 indent_style = tab
-
-[*.md]
-trim_trailing_whitespace = false

.markdownlint.json

@@ -0,0 +1,9 @@
+{
+  "no-inline-html": false,
+  "line-length": false,
+  "no-trailing-punctuation": false,
+  "no-duplicate-header": false,
+  "first-header-h1": false,
+  "first-line-h1": false,
+  "commands-show-output": false
+}

Makefile

@@ -35,6 +35,7 @@ clean:
 lint:
 	@printf "==> [Test :: Lint]\n"
 	npm run lint
+	npm run markdownlint
 
 test-node: test-bdd test-tdd test-qunit test-exports test-unit test-integration test-jsapi test-compilers test-requires test-reporters test-only test-global-only
 

package.json

@@ -300,6 +300,7 @@
   },
   "scripts": {
     "lint": "eslint . bin/*",
+    "markdownlint": "markdownlint \"*.md\" \"docs/**/*.md\" \".github/*.md\"",
     "test": "make clean && make test",
     "prepublishOnly": "npm test && make clean && make mocha.js",
     "coveralls": "nyc report --reporter=text-lcov | coveralls",
@@ -321,6 +322,7 @@
     "supports-color": "4.4.0"
   },
   "devDependencies": {
+    "@mocha/markdownlint-cli": "^1.0.0",
     "assert": "^1.4.1",
     "browserify": "^14.4.0",
     "buffer": "^4.9.1",