Initial version of the new Docker Build scripts

Successfully builds the container, places the files, scripts and links
we need so fart into the right places using a rootfs tar file so that we
don't pollute the container unneccessarily and keep the Dockerfile
simple.

Any in-container scripting is missing so far, so the whole thing does
not yet start up successfully or popluate the config share in any way.
That is for another day.

src/db.inc.php

@@ -0,0 +1,15 @@
+<?php
+include_once("/var/roundcube/config/db.inc.php");
+
+switch ($dbtype) {
+ case "sqlite":
+   $config['db_dsnw'] = "sqlite:///$basepath/$dbname?mode=0640";
+   break;
+ default:
+   if ($dbport != '') $dbport=":$dbport";
+   if ($dbserver == '') $dbserver="localhost";
+   $config['db_dsnw'] = "$dbtype://$dbuser:$dbpass@$dbserver$dbport/$dbname";
+   break;
+ }
+?>
+