tutorial additions

[brownd1978]

Include an exercise creating/running an event loop macro for the next tutorial Include an exercise using TrkAnaUtil to browse the TrkAna trees Include a real tutorial using Crv branches

[sophiemiddleton]

Would also be good to incorporate more diverse tutorial task, and advanced tasks linked to real analysis-type skills. I will do this as part of the Reference Analysis effort

[AndrewEdmonds11]

From Sophie in #153:

we should include some real examples for analysis
we should look at some extracted analysis too

[sophiemiddleton]

thanks Andy, I thought I remembered writing this somewhere