New Tutorials: UCESB Reader and Mapping File

Currently, the work is ongoing on connecting UCESB and R3BRoot. The goal is to have mapped raw data saved to a tree as arrays of R3BRoot objects. A working prototype is available in the dev branch on GitHub, together with example readers for event header and NeuLAND. New Tutorials have been added to the section "For Developers" in menu "Documentation": "Add UCESB Reader" and "Create Mapping for Unpacker". They describe instructions on adding support for a new detector into current scheme. Your feedback and corrections are welcome.