Task scripts are not properly handled when hot-swapping tasks

[philippotto]

Context

Finishing a task and starting a new one via "Finish and get next task" doesn't work correctly when scripts are involved. For example, a script which shows a message upon task start, won't show that message when the second task was started.

Expected Behavior

Ideally, each task script should be terminated when a task is done, and the new task script should be started.

Current Behavior

Currently, the page reloads if the task script changes. If the script does not change, the script simply stays alive for the new task. If it does the correct thing, is implementation specific.

Steps to Reproduce the bug

1. Create task with script which outputs something upon start
2. Switch from one task to another with "finish and get next task"
3. see that the output only is created once.

Your Environment for bug

• Browser name and version: e.g. Chrome 39
• Operating System and version: e.g. Windows 10
• Version of WebKnossos (Release or Commit):
  irrelevant