DataCheck handling (CB hole problem) and proper scaler storage

New additions to handle rejection of data due to missing CB sections (now a reasonably common data issue). Also, proper storage of scalers is now done. TraverseEntries - the original routine to step through data is replaced by a routine to step through the data scaler read by scaler read. If the data passes any data checks turned on, the events within a scaler read are analysed and the corresponding scaler read is stored.
Traverse Acqu Entries improved for MC data handling

Call to open Scaler tree will not fail GoAT running (this change is required to match current output from Acqu which does not produce the scaler tree for MC data). Routine to traverse entries is also renamed back to TraverseAcquEntries for consistancy.
File handling controls in PPi0

Small fixes for file handling in class PPi0.
Restructuring of folder structure!
Edit of example GoAT config files after folder restructure.

Folder of 2D cut (examples) was moved down a directory, the appropriate lines in the example config giles have been editted.
ParticleReconstruction: Corrections in MesonReconstruction()
Changes to Particle reconstruction - pi0 reconstruction

Meson reconstruction now allows for the reconstruction of pi0 from more than two tracks (as part of the reaction p4 test). This is needed as split-offs (common) are not handled properly in AcquRoot. Since this check is allowed for eta and eta-prime it should also be allowed for pi0 reconstruction. This should be reevaluated if we ever include a proper split-off search into AcquRoot.
Small correction to scaler storage

Small correction to scaler storage for the proper rejection of events missing a scaler readout.
Missing four-vector routine from physics library class

An additional physics routine is provided which returns the missing Lorentz Vector calculated from a tagger electron index and particle index.
Added build directory to gitignore