Refactor usage pattern of xmldoc info tag.

This updates func_channel.c and main/message.c to use a generic xpointer
include instead of including info from each channel driver.  Now the
name attribute of info is CHANNEL or CHANNEL_EXAMPLES to be included in
documentation for func_channel.  Setting the name attribute of info to
MessageToInfo or MessageFromInfo causes it to be included in the
MessageSend application and AMI action.

Change-Id: I89fd8276a3250824241a618009714267d3a8d1ea

doc/appdocsxml.xslt

@@ -6,7 +6,10 @@
 
     <xsl:template match="node()|@*">
         <xsl:copy>
-            <xsl:apply-templates select="node()|@*"/>
+            <xsl:for-each select="node()|@*">
+                <xsl:sort select="@tech"/>
+                <xsl:apply-templates select="."/>
+            </xsl:for-each>
         </xsl:copy>
     </xsl:template>