RTC::Timer fixes, example program

Well, this isn't the pull request I expected... Here's what I did:
        1. shell `git fetch upstream`
        2. shell `git merge upstream/master`
        3. github for Windows synch on my repo (I did not expect to have to do this)
        4. edit files
        5. gfW commit to my repo
        6. pull request
However, it seems like the diff is from your last pull, even though I started with your "Rectoring..." 5690e1fbec1db8dee81e1ff587797260eff3bae3.  These steps are what I did last time... should I be doing something else?  The first time, I made a branch of my repo, and the pull request was for the branch.  After the pull request was accepted, the branch was deleted.  Sigh.  I'm thinking maybe gfW is too simplistic.  Or I am.

Also apologies if RTCMeasure.* are in the wrong directory.  They compile to nothing if the define is off, so it doesn't hurt.  Because it's coupled to RTC::Timer (as a friend class), I put it there for now.  As fairly pure instrumentation code, maybe it should go elsewhere?

There is another question at RTC.cpp line 98.

Thanks!