Add markdown format support (#25)

Co-authored-by: Dawid Dziurla <dawidd0811@gmail.com>

node_modules/yargs-parser/lib/tokenize-arg-string.js

@@ -0,0 +1,40 @@
+// take an un-split argv string and tokenize it.
+module.exports = function (argString) {
+  if (Array.isArray(argString)) {
+    return argString.map(e => typeof e !== 'string' ? e + '' : e)
+  }
+
+  argString = argString.trim()
+
+  var i = 0
+  var prevC = null
+  var c = null
+  var opening = null
+  var args = []
+
+  for (var ii = 0; ii < argString.length; ii++) {
+    prevC = c
+    c = argString.charAt(ii)
+
+    // split on spaces unless we're in quotes.
+    if (c === ' ' && !opening) {
+      if (!(prevC === ' ')) {
+        i++
+      }
+      continue
+    }
+
+    // don't split the string if we're in matching
+    // opening or closing single and double quotes.
+    if (c === opening) {
+      opening = null
+    } else if ((c === "'" || c === '"') && !opening) {
+      opening = c
+    }
+
+    if (!args[i]) args[i] = ''
+    args[i] += c
+  }
+
+  return args
+}