timing: Improve performance for most timing implementations.

This change allows timing implementation data to be stored directly
on the timer itself thus removing the requirement for many
implementations to do a container lookup for the same information.

This means that API calls into timing implementations can directly
access the information they need instead of having to find it.

Review: https://reviewboard.asterisk.org/r/3175/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@407749 65c4cc65-6c06-0410-ace0-fbb531ad65f3