We encountered a bug #39 that caused DotConverter to fail sometimes.
After debugging backend we noticed that DotConverter is trying to be
evaulated with templateParams 'automaton::Automaton' which was weird.
(It could be also noticed from the JSONs sent to backends, but I was
super blind.)

After some messing with the frontend it seemed that DotOutput node (when
put) on the canvas already has the templateParams set wrong. It seemed
that this happens only when putting it on the canvas after a node that
has templateParams specified (like string::Parse).

The solution is therefore to set templateParams to empty before putting
any special node on canvas.

Closes #39.