Remove mysql - this should fix issue 29 - namely removal of most mysql_ function calls see issue #29

I've refactored the code to remove the direct dependency on MySQL for all code outside of the 'setup' directory. i.e. mysql_query(), mysql_real_escape_string(), mysql_fetch_array() etc have been replaced/removed.

This should make it a lot easier to support PHP 5.6, or port it to another database (like sqlite)

All database calls are now made through the db_query() or db_query_one() functions. 

Supporting another database should just now be a case of changing the database_library.php file to use a different database backend.

These commits should also include a large number of SQL injection fixes.

See also issue #29