title: Valid characters for app names
body: <p>Are there any rules that limit what characters may be used for naming apps on the Android and Apple app stores.  For instance, is there a constraint that</p>
  
  <ul>
  <li>restricts the name length. I have come across suggestions that a good name should have 12- characters.</li>
  <li>limits the name to contain only alphanumeric characters</li>
  <li>is it possible to use any unicode character in an app name</li>
  </ul>