implemented init method on model
made model c'tor final
added small comment to model init
added flags param to ModelRow::toData method
Phire\Router::show404() method updated to set 404 status header
Output process changed around, no longer sending output on controller d'tor
as when re-dispatching to show404 output being sent prematurely
Output::flush() set as shutdown function in bootstrap
die_var using Phire\Output and output buffer