Improved functional handler. Instead of event name handler function takes event_t object that provides upstream. Having ustream function can send more than one chunk as answer or doesn't send chunks at all. For example, it's possible to process http requests in function with this new handler. Also in this commit default on_error method of basic_handler_t is added. I don't know why somebody may want to send error to application, so i don't want to write emty on_error method in every handler.
Merge branch 'new_handlers'