MCPL 1.1.0

This MCPL version brings several improvements. Improve unit vector packing scheme for higher precision in stored particle directions (older files using the previous packing scheme are of course still readable). Improve MCNP converters ssw2mcpl and mcpl2ssw to support more files (including MCNP5 files and files from in-house MCNP builds). Interfaces for file merging is now more user-friendly. Add option for universal weights, allowing smaller files in case of unweighted particles. Improve documentation in release and add more build mechanisms for "fat" files. Add small sample MCPL file (example/example.mcpl) to release. And much more. Refer to the CHANGELOG file for details.This work was supported in part by the European Union's Horizon 2020 research and innovation programme under grant agreement No 676548 (the BrightnESS project) and under grant agreement No 654000 (the SINE2020 project)