textile-double-escape-bug.t: tolerate any valid encoding Discount in current Debian unstable turns the IURI href into a URI by encoding the Unicode as UTF-8 and %-escaping each byte. That is valid, and matches Wikipedia's expectations, but was breaking this test for me. It would also be entirely valid (and lead to equivalent parsing) if the รถ was represented as ö, ö or ö in the text and/or the href.
Work around Debian #771047: use a non-blank SVG for the regression test Inkscape loses the bounding box of a SVG with no content when it converts it to EPS, and ImageMagick does not have a special case for converting SVG to PNG with Inkscape in one step (which Inkscape can do); it prefers to convert SVG to EPS with Inkscape, then EPS to whatever.
Always produce HTML5 doctype and new attributes, but not new elements According to caniuse.com, a significant fraction of Web users are still using Internet Explorer versions that do not support HTML5 sectioning elements. However, claiming we're XHTML 1.0 Strict means we can't use features invented in the last 12 years, even if they degrade gracefully in older browsers (like the role and placeholder attributes). This means our output is no longer valid according to any particular DTD. Real browsers and other non-validator user-agents have never cared about DTD compliance anyway, so I don't think this is a real loss.