Avoid loosing work when the csrf tickets expire

Working with diagrams is a bit more complicated than working with text. First, Tiki does not alert about csrf ticket expiration on the diagrams tool. So, after some time, if the user didn't save his work he might lose all the content he produced. This merge-request has code that attempt to renew the csrf tokens before saving the diagrams. I had to rewrite some chunks of the code to insert my strategy, so I guess a review on that is very welcome.