title: Finding a way to get the Library Version used?
body: <p>I am deploying a script on multiple spreadsheets via the Libraries.
  But as you may know, there is no way (yet) for the script to know if it's running the latest version. </p>
  
  <p>I am trying to find a way around this by creating my own versioning for my code.
  I have a web service giving back the latest version number of my library code so I can compare it, but the onOpen() cannot run fetchURL. I tried opening a spreadsheet that would keep the info, but again the onOpen() do not let you openById... </p>
  
  <p>onOpen() trigger has security limitations that prevent me to consult an external data source that I could use to keep my versioning.</p>
  
  <p>Note: I do not want to use script trigger for the onOpen() event. Script trigger are not copied when the spreadsheet is copied.</p>
  
  <p>So I am running out of ideas on how to check a library version on a onOpen() trigger event by pointing on an external data source (being a url, other spreadsheet - anything!).</p>
  
  <p>Any suggestions?</p>