Directly edit properties on original cue.
Make toJSON method return a string.
Merge branch 'master' of github.com:tomayac/postdoc

* 'master' of github.com:tomayac/postdoc:
  Related Work on Popcorn.js and PocornMaker.
  WebCHM model. SMIL Timesheets.
  Related work around SMIL.