Remove indent="yes" from test stylesheets.

Remove indent="yes" from test stylesheets.

Make a copy of a each stylesheet without indent="yes" and work with that
copy instead.

For now, don't write trailing whitespace at the end of the document.

In test comparisons, ignore leading whitespace at the beginning of the
document and trailing whitespace at the very end.
  - Don't ignore whitespace in the middle of the document though!)
  - Do it this way so that we don't trip over the extra whitespace
    xsltproc writes at the end, and similarly to avoid issues between
    the XMLDecl and root element.
  - Might still hide mistakes when the output is not a well-formed XML
    document, e.g. when writing only a text node, but that's probably
    not too important.