Support stylesheets with different output methods than XML

[evanlenz]

The solution for #5 raised a problem for trace-enabled stylesheets that output a different format than XML (such as text). When the delivery-format for transform() is "document" (the default), the output method of the user stylesheet is disregarded.

I have a solution pending that uses "serialized" as the delivery-format, but that runs afoul of an apparent Saxon bug that gets exploited when, for example, xsl:output/@method is "text". Keep the solution around in disabled form for when the bug has been fixed for a while (or I learn what I might have been doing wrong).

In the meantime, provide a workaround that enables us to pass in the principal-output-method as a parameter to run-trace.xsl. Yes, we have to repeat ourselves, but it's not too big a deal as far as workarounds go.