Major step towards replay - please smoke-test

[Eric S. Raymond]

Hal, please review my commit "Isolate the ntpd main loop into a
mainloop() function." and smoke-test the ntpd repo head.

This is a simple but large refactoring attempt; I don't think it
busted anything, but I'd like to be sure.

Breakage to watch for, if there's anything, would be associated with
timers.  I moved the initialization point of that code and put a guard
on the reinitializationn in the loop filter.

If nothing goes *sproing*, this is a really major step towards replay
mode working.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>