trkcalohitmc has 2 vectors per event?

[AndrewEdmonds11]

In #262, Leo reports that the trkcalohitmc branch has two vectors. I think these are for the two downstream fits that assign calorimeter hits to the track (upstream fits do not do this). We need to understand whether we want to add empty vectors so that the trkcalohitmc branch has four vectors like the other track branches. We should:

• confirm that the two vectors currently in trkcalohitmc are from the downstream fits
• find how many vectors are in trkcalohit (is it the same number or different?)
• decide how we want to handle these