Doc: revise formatting of function/operator tables.

The table layout ideas proposed in commit e894c618 were not as widely
popular as I'd hoped.  After discussion, we've settled on a layout
that's effectively a single-column table with cell contents much like a
<varlistentry> description of the function or operator; though we're not
actually using <varlistentry>, because it'd add way too much vertical
space.  Instead the effect is accomplished using line-break processing
instructions to separate the description and example(s), plus CSS or FO
customizations to produce indentation of all but the first line in each
cell.  While technically this is a bit grotty, it does have the
advantage that we won't need to write nearly as much boilerplate markup.

This patch updates tables 9.30, 9.31, and 9.33 (which were touched by
the previous patch) to the revised style, and additionally converts
table 9.10.  A lot of work still remains to do, but hopefully it won't
be too controversial.

Thanks to Andrew Dunstan, Pierre Giraud, Robert Haas, Alvaro Herrera,
David Johnston, Jonathan Katz, Isaac Morland for valuable ideas.

Discussion: https://postgr.es/m/8691.1586798003@sss.pgh.pa.us

doc/src/sgml/stylesheet-common.xsl

@@ -103,4 +103,11 @@
   <xsl:apply-templates select="." mode="xref"/>
 </xsl:template>
 
+
+<!-- Support for explicit line breaks <?br?> within table cells -->
+
+<xsl:template match="processing-instruction('br')">
+  <br/>
+</xsl:template>
+
 </xsl:stylesheet>

doc/src/sgml/stylesheet-fo.xsl

@@ -63,6 +63,32 @@
   </fo:inline>
 </xsl:template>
 
+<!-- overrides built-in DocBook template -->
+<xsl:template name="table.cell.block.properties">
+  <!-- highlight this entry? -->
+  <xsl:choose>
+    <xsl:when test="ancestor::thead or ancestor::tfoot">
+      <xsl:attribute name="font-weight">bold</xsl:attribute>
+    </xsl:when>
+    <!-- Make row headers bold too -->
+    <xsl:when test="ancestor::tbody and
+                    (ancestor::table[@rowheader = 'firstcol'] or
+                    ancestor::informaltable[@rowheader = 'firstcol']) and
+                    ancestor-or-self::entry[1][count(preceding-sibling::entry) = 0]">
+      <xsl:attribute name="font-weight">bold</xsl:attribute>
+    </xsl:when>
+  </xsl:choose>
+  <!-- Postgres additions start here -->
+  <!-- indent all but first line of entries in tables of functions -->
+  <xsl:choose>
+    <xsl:when test="self::entry[@role='functableentry']">
+      <xsl:attribute name="margin-left">5em</xsl:attribute>
+      <xsl:attribute name="text-indent">-5em</xsl:attribute>
+      <xsl:attribute name="text-align">left</xsl:attribute>
+    </xsl:when>
+  </xsl:choose>
+</xsl:template>
+
 <!-- overrides stylesheet-common.xsl -->
 <!-- FOP needs us to be explicit about the font to use for right arrow -->
 <xsl:template match="returnvalue">
@@ -70,6 +96,11 @@
   <xsl:call-template name="inline.monoseq"/>
 </xsl:template>
 
+<!-- overrides stylesheet-common.xsl -->
+<xsl:template match="processing-instruction('br')">
+  <fo:block/>
+</xsl:template>
+
 <!-- bug fix from <https://sourceforge.net/p/docbook/bugs/1360/#831b> -->
 
 <xsl:template match="varlistentry/term" mode="xref-to">

doc/src/sgml/stylesheet.css

@@ -76,6 +76,20 @@ div.example {
 	margin: 0.5ex;
 }
 
+/* formatting for entries in tables of functions: indent all but first line */
+
+th.functableentry {
+	padding-left: 5em;
+	text-indent: -5em;
+	text-align: left;
+}
+
+td.functableentry {
+	padding-left: 5em;
+	text-indent: -5em;
+	text-align: left;
+}
+
 /* Put these here instead of inside the HTML (see unsetting of
    admon.style in XSL) so that the web site stylesheet can set its own
    style. */