Use detection bin symmetry in efficiencies and alive-time

[KrisThielemans]

Fixes #138
Fixes #171
Fixes #157

Also

• renamed moduleCoincidenceAliveTimeFractions to modulePairAliveTimeFractions for consistency with modulePairEfficiencies
• changed SGID type from uint to int, as we use -1 to denote "not in coincidence"

[KrisThielemans]

Model changes and C++ hopefully finished. Python still to do.

[KrisThielemans]

Current status:

• run-time errors in the Python code due to modulePairEfficiencies, see also Symmetry in module-pair efficiencies/alive-time #138 (comment). Confusingly, no run-time errors in the C++ code.
• Still need to adapt the ScannerInformation TOF fields to be lower_triangular in module_type, but that's a trivial change.