Changes:
* fixed bug for an LHE input only with anti-particles
* fixed error that truncated signal yields when computing expected upper limits
* added minMass parameter for setting a minimum mass threshold for BSM masses
* fixed C++ interface to work with python 3.11
* bumped up pythia8 from 8.307 to 8.308
* SModelS can now track inter-analyses combinability at the level of whole
analyses as well as individual signal regions via a combinations matrix
* added support for SLv2 (Gaussian with a skew), arXiv:1809.05548
* refactored the statistics modules, code ready for interfacing Spey
* introduced "full_llhds" database add-on (see parameters.ini file)