Sanitize tokens from smarty statements when templates are evaluated with civicrm tokens and smarty tokens

Reported by Tim otten. We should do two things:

1. ensure we turn on smarty security in this mode to make the evaluation more secure

2. convert '

{' and '}

' to

{ldelim}

and

{rdelim}

so that any potential commands embedded in the database are not interpreted as smarty commands