[ssl] accept ssl renegotiations if they are not disabled (fixes #2491)

 * don't fiddle with ssl internals
 * renegotiations should be safe with recent openssl versions,
   openssl itself should reject unsafe renegotiations

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2890 152afb58-edef-0310-8abb-c4023f1b3aa9
[ssl] add option ssl.empty-fragments, defaulting to disabled (fixes #2492)

  if ssl.empty-fragments is set to enabled, but the openssl version used
  to compile lighttpd doesn't support empty fragments, a warning is
  displayed (it might still work).

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2891 152afb58-edef-0310-8abb-c4023f1b3aa9
[auth] put REMOTE_USER into cgi environment, making it accessible to lua via lighty.req_env (fixes #2495)

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2892 152afb58-edef-0310-8abb-c4023f1b3aa9
[mod_auth] some cleanup, only search for matching auth.require path once

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2893 152afb58-edef-0310-8abb-c4023f1b3aa9
[auth] new method "extern" to use already present REMOTE_USER (from magnet, ssl, ...) (fixes #2436)

  can be combined with ssl:
    ssl.verifyclient.username = "SSL_CLIENT_S_DN_UID"
	auth.require = ("/" => ( "require" => "valid-user", "method" => "extern") )

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2894 152afb58-edef-0310-8abb-c4023f1b3aa9
[core] remove requirement that default doc-root has to exist, there are reasonable scenarios not requiring static files at all

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2895 152afb58-edef-0310-8abb-c4023f1b3aa9
[core] check whether server.chroot exists

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2896 152afb58-edef-0310-8abb-c4023f1b3aa9
[tests] add mod_simplevhost tests

  * next commit fixes the bug

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2897 152afb58-edef-0310-8abb-c4023f1b3aa9
[mod_simple_vhost] fix cache; skip module if simple-vhost.server-root is empty (thx rm for reporting)

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2898 152afb58-edef-0310-8abb-c4023f1b3aa9