Calibration and test updates for v2.6 using Geant4 (v 11.1.ref05)

[DandreaMichele]

I report a brief summary of the commits generated for the three modified files (ATLHECTBanalysis1_v2p6.C, emanalysis.h, pianalysis.h) :

• ATLHECTBanalysis1_v2p6.C: Updated the reconstructed e- energies to the G4.11.1.ref05 version (v2.6)
• emanalysis.h: Updated the SampFraction to the new G4.11.1.ref05 version (v2.6), updated the names of the Canvas legends to G4.11.1.ref05 (v2.6), Changed the initialization of the double variables by setting them to 0. at the start.
• pianalysis.h: Updated the SampFraction to the new G4.11.1.ref05 version (v2.6), updated the names of the Canvas legends to G4.11.1.ref05 (v2.6), Changed the initialization of the double variables by setting them to 0. at the start.

[lopezzot]

Approving PR #22.

[lopezzot]

PR #22 contains the first changes for the CERN 2023 Summer School project. ATLHECTB 2.6 will be released soon and will contain the changes to handle the CERN.FLUKA interface as well as the analysis tools for the G4-to-CERN.FLUKA results comparison. This PR changes analysis files within v2.6 directory and adds the new sampling fraction value obtained with Geant4-11.1.ref05, FTFP_BERT, and the current master of ATLHECTB. It also fixes a bug in analysis initializing uninitialized doubles to 0.