Revert "Doc: Modify \tabcontent..\endtabcontent macros"

This reverts commit 5c0b08a20d.

After the original commit, DocBook support for tabbed
content was introduced (as format-specific macros). This
means that the original macros will also have to be HTML-format
specific, as macros cannot have both default and
format-specific variants defined.

In addition to reverting, add linefeeds to (end)tabcontent.HTML
macros to solve the same problem that the reverted commit did.

In passing, fix an issue with the tabcontent.DocBook macro; it
takes a single argument, therefore the placeholder for the
value must be \1.

Change-Id: I90ed6bc37d70c10754b3b810198ac44fcd189766
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: David Boddie <david.boddie@qt.io>

doc/global/htmltabs.qdocconf

@@ -38,12 +38,12 @@
 #   \endtabcontent
 # \endif
 
-macro.tab.HTML = "<input type=\"radio\" name=\"tabs_\1\" id=\"\2\" \4/><label for=\"\2\">\3</label>\n<style>#\2:checked ~ .\2{display: block;}</style>\n"
-macro.tabcontent = "\\div {class=\"tabcontent \1\"}"
-macro.endtabcontent = "\\enddiv"
+macro.tab.HTML = "<input type=\"radio\" name=\"tabs_\1\" id=\"\2\" \4/><label for=\"\2\">\3</label><style>#\2:checked ~ .\2{display: block;}</style>"
+macro.tabcontent.HTML = "<div class=\"tabcontent \1\">\n"
+macro.endtabcontent.HTML = "</div>\n"
 
 macro.tab.DocBook = "<db:bridgehead xml:id="\2" renderas="sect5" role="tabbed \4 tab-group_\1" xlink:href="#\2_contents">\3</db:bridgehead>"
-macro.tabcontent.DocBook = "<db:sidebar xml:id="\2_contents">"
+macro.tabcontent.DocBook = "<db:sidebar xml:id="\1_contents">"
 macro.endtabcontent.DocBook = "</db:sidebar>"
 
 HTML.extraimages += template/style/htmltabs.css