[timers] Add ability to detect and reschedule timers that occur at the same time

[rkoshak]

Now that we have a centralized place where timers are actually created, add some bookkeeping there to keep track of when all the outstanding timers are scheduled to go off and avoid collisions. I'm thinking that if they are within 250 msec that we move the new timer forward half a second. Don't forget to clean up the book keeping to avoid a memory leak.