Changed io::read/write to not use a loop and return a count of successfu...

changed io::read/write to not use a loop and also return a uint of the count that they wrote or read. 
added reregister and register_opt functions to event_loop and the pollers that it uses.  
moved event_loop::connect into net::
Should this not be event::EDGE instead of event::LEVEL?
Seems to cause the event loop to constantly wake up otherwise (on linux atleast)