v2.1-b3

Ask @lvkaszus! - version: 2.1-b3 (2.1-build3)

Changelog:

• Documentation: Added legacy documentation for this application - Documentation for the v3.xx version is not compatible with this and older v2.xx releases of this application!
• Frontend & Admin Panel & Backend: Making this project up to date by updating every library used in the source code of this app!