Add TimeoutAbs - version of Timeout class that takes absolute time instead of relative and fires only once. Based on that also add optimized version of Timeout that only need to fire once.
Add TimeoutAbs - version of Timeout class that takes absolute time instead
of relative and fires only once. Based on that also add optimized version
of Timeout that only need to fire once.

AVOXI/b2bua,sippy/b2bua,AVOXI/b2bua,sippy/b2bua