EPUB2/3 templates: Move inline styles to default epub.css.

Those who use a custom CSS stylesheet with EPUB should
add these lines:

```css
code{ white-space: pre-wrap; }
span.smallcaps{ font-variant: small-caps; }
span.underline{ text-decoration: underline; }
q { quotes: "“" "”" "‘" "’"; }
div.column{ display: inline-block; vertical-align: top; width: 50%; }
```

See #5466.

data/epub.css

@@ -17,3 +17,8 @@ nav#landmarks ol li { list-style-type: none; margin: 0; padding: 0; }
 a.footnote-ref { vertical-align: super; }
 em, em em em, em em em em em { font-style: italic;}
 em em, em em em em { font-style: normal; }
+code{ white-space: pre-wrap; }
+span.smallcaps{ font-variant: small-caps; }
+span.underline{ text-decoration: underline; }
+q { quotes: "“" "”" "‘" "’"; }
+div.column{ display: inline-block; vertical-align: top; width: 50%; }

data/templates/default.epub2

@@ -6,15 +6,6 @@
   <meta http-equiv="Content-Style-Type" content="text/css" />
   <meta name="generator" content="pandoc" />
   <title>$pagetitle$</title>
-  <style type="text/css">
-      code{white-space: pre-wrap;}
-      span.smallcaps{font-variant: small-caps;}
-      span.underline{text-decoration: underline;}
-      div.column{display: inline-block; vertical-align: top; width: 50%;}
-$if(quotes)$
-      q { quotes: "“" "”" "‘" "’"; }
-$endif$
-  </style>
 $if(highlighting-css)$
   <style type="text/css">
 $highlighting-css$

data/templates/default.epub3

@@ -5,15 +5,6 @@
   <meta charset="utf-8" />
   <meta name="generator" content="pandoc" />
   <title>$pagetitle$</title>
-  <style>
-      code{white-space: pre-wrap;}
-      span.smallcaps{font-variant: small-caps;}
-      span.underline{text-decoration: underline;}
-      div.column{display: inline-block; vertical-align: top; width: 50%;}
-$if(quotes)$
-      q { quotes: "“" "”" "‘" "’"; }
-$endif$
-  </style>
 $if(highlighting-css)$
   <style>
 $highlighting-css$