More usable sentence modification

[nschneid]

Right now, in edit mode, the tokens can be adjusted, but any change to the tokenization requires updating numeric indices. This includes when adding a gap.

Idea: double-clicking the sentence at the top of the page makes it an editable text field. After update, the sentence can be re-parsed. Probably should be deactivated in edit mode.

[bwaldon]

Addressed by bwaldon@4c9fc55

Still todo:

• Somehow indicate visually for the user that the sentence is editable (e.g., by cursor change)
• Replace clunky DOM editing with jQuery