[GREENFOOT-403] Export to webpage when project name has a space produces invalid output

If you export a scenario whose name contains a space (or various other characters) to a web page, the resulting applet tag contains an invalid 'archive' attribute containing the unencoded scenario name. It should be URL-encoded. The applet won't run due to this problem.

eg: archive="test scenario.jar"

should be:

 archive="test%20scenario.jar"

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Issue metadata

• Issue type: Bug
• Priority: Low
• Fix versions: 2.4.0