(1)

Implement "visual" tracing by using an prebuild clip with Ming.
This will allow us to *NOT* use the drawing API, which was only
introduced in SWF6 and thus prevents us from "visually" testing
previous SWF versions.

Note that a known-to-work way would be using the "import" feature
of 'makeswf' (-i flag), but then we'd need a run-time loading
which might make it harder to transport testcases (the 'imported'
file would need to lay around).

Note also that the 'prebuilt' clip feature is a pretty new one, so
might need some work on the Ming side (including support for
prebuild clips in the command-line compiler)

P T Withington <ptw@openlaszlo.org> says:
"In the real SWF player, calling undefined is not fatal,
 it returns undefined and continues." (we should check we do this too)
