Importer must handle underlined whitespace at the start of a line

[goose-life]

This isn't stripped in general, because it's potentially significant, but leads to overindentation when it's at the start of a hierarchical element.

<p><u>	(e)</u>	underlined whitespace before e, overindented</p>
<p><u> </u>(f) underlined whitespace before f, overindented</p>

output (note over-idented):

  PARAGRAPH (e)
     underlined whitespace before e, overindented
  PARAGRAPH (f)
     underlined whitespace before f, overindented