jcoder 0.5.4

• No more running out of memory. jcoder left waiting (a question, a
  long command) ran the heap out after a few hours: React's development
  build kept a timing record for every redraw of the spinner, and the
  live area's measuring held on to two updates per frame. jcoder now loads
  React's production build and only measures when the size changes. Your own
  NODE_ENV still reaches the commands it runs.