Calibrations for the ATHENA detector

Calibrations and constants for this ATHENA detector setup. These values are used in the reconstruction. Each relevant subsystem that requires calibration data should have its own subdirectory with relevant calibration files, preferably in JSON format.

Note that these calibrations are strongly versioned and tied directy to this specific detector configuration. Therefore, please do not add an extra layer of versioning in the file names, but rather only add those calibrations relevant for this particular setup.