new editor

- this pull request is OPTIONAL

* index.html is switched with the new livecode editor. (index.html --> old_index.html)
* font size/ box height adjusted for the new editor, extend box is removed. 
* selective execution possible by selecting text and pressing Cmd+R or Ctrl+R  (like supercollider) for live coding
-->Be careful not to run Cmd R when textarea is not focused. It will refresh the page and you will lose your code.

Note that we have not generated flowbox.md.