NTuple additions for NuMI nue pi+-

[pgreen135]

Adds several variables to the ntuples for the numi nue pi+- analysis:

• adds track trunk dE/dx and pion bragg peak score to TrackAnalysis_tool
• adds tertiary track and shower index information to CC0piNp analyser

I've tried to keep a similar structure to the existing code, please let me know if anything should be changed / moved.