Code style improvements from the reviews of
* Rename ´$serendipity['title_first'´] to
´$serendipity['backendBlogtitleFirst']´ and
make it boolean
* Add default to `serendipity_config.inc.php`.
* Change the condition in ´2k11/admin/index.tpl´
that the first branch is run by default
Signed-off-by: Thomas Hochstein <thh@inter.net>