Add more drop tables, fix nexid def in mysql newtables

setup/sql/mysql_newtables.inc.php

@@ -342,7 +342,7 @@
   $phpgw_setup->db->query($sql); 
 
   $sql = "create table phpgw_nextid (
-           appname varchar(25),
+           appname varchar(25) NOT NULL,
            id      int(8),
 		   UNIQUE (appname)
           )";