Update <hgroup> children after first <h#> to <p>, ref. new HTML standard

src/epub/text/agrarian-justice.xhtml

@@ -17,7 +17,7 @@
 			<section id="agrarian-justice-authors-inscription" epub:type="z3998:subchapter">
 				<hgroup>
 					<h3 epub:type="title">Author’s Inscription</h3>
-					<h4 epub:type="subtitle">To the Legislature and the Executive Directory of the French Republic</h4>
+					<p epub:type="subtitle">To the Legislature and the Executive Directory of the French Republic</p>
 				</hgroup>
 				<p>The plan contained in this work is not adapted for any particular country alone: the principle on which it is based is general. But as the rights of man are a new study in this world, and one needing protection from priestly imposture, and the insolence of oppressions too long established, I have thought it right to place this little work under your safeguard. When we reflect on the long and dense night in which France and all Europe have remained plunged by their governments and their priests, we must feel less surprise than grief at the bewilderment caused by the first burst of light that dispels the darkness. The eye accustomed to darkness can hardly bear at first the broad daylight. It is by usage the eye learns to see, and it is the same in passing from any situation to its opposite.</p>
 				<p>As we have not at one instant renounced all our errors, we cannot at one stroke acquire knowledge of all our rights. France has had the honour of adding to the word <em>Liberty</em> that of <em>Equality</em>; and this word signifies essentially a principal that admits of no gradation in the things to which it applies. But equality is often misunderstood, often misapplied, and often violated.</p>

src/epub/text/anti-monarchal-essay.xhtml

@@ -9,7 +9,7 @@
 		<section id="anti-monarchal-essay" epub:type="chapter">
 			<hgroup>
 				<h2 epub:type="title">Anti-Monarchal Essay</h2>
-				<h3 epub:type="subtitle">For the Use of New Republicans<a href="endnotes.xhtml#note-5" id="noteref-5" epub:type="noteref">5</a></h3>
+				<p epub:type="subtitle">For the Use of New Republicans<a href="endnotes.xhtml#note-5" id="noteref-5" epub:type="noteref">5</a></p>
 			</hgroup>
 			<p>When we reach some great good, long desired, we begin by felicitating ourselves. We triumph, we give ourselves up to this joy without rendering to our minds any full account of our reasons for it. Then comes reflection: we pass in review all the circumstances of our new happiness; we compare it in detail with our former condition; and each of these thoughts becomes a fresh enjoyment. This satisfaction, elucidated and well-considered, we now desire to procure for our readers.</p>
 			<p>In seeing Royalty abolished and the Republic established, all France has resounded with unanimous plaudits.<a href="endnotes.xhtml#note-6" id="noteref-6" epub:type="noteref">6</a> Yet some who clap their hands do not sufficiently understand the condition they are leaving or that which they are assuming.</p>