[sr-dev] script callbacks

Hi Andrei, could you please have a look at the tirpi/script_callbacks branch? There are some modules that need to initialize their variables before, or free/unlock/unref,... something after the script executions. This is supported only for request and onreply routes, but it is necessary also before/after failure routes in some cases. (For example db_ops needs to free the query result.) So I started to add support for pre- and post-script callbacks for failure routes. But instead of simply adding another list to the core I generalized the API a bit to support any kind of route blocks, and added hooks also for branch and onsend routes. Please let me know whether I can merge my branch to the master. Daniel: shall I add a hook around modules_k/htable/htable.c:187 for event_route? Thanks, Miklos