timer.rb

changes:

 1. Timer::Timer ---> Timer
 2. timer id is now the object_id of the action
 3. Timer resolution removed, we're always arbitrary precision now
 4. I don't see any obvious races [not that i did see any in old impl, though]
 5. We're tickless now, so no need to jerk start/stop
 6. We should be pretty fast now, wrt old impl
 7. reschedule/remove/block now accept nil as an action id (meaning "current")
 8. repeatability is ignored for 0-period repeatable timers
 9. configure() method superceeds reschedule() [the latter stays as compat]

Required files