Began with splitting up Handler.cpp

- Created Map class
- Created GameSession class
- Extended ClientInfo class
- Updated/fixed chat function
Revert "Began with splitting up Handler.cpp"

This reverts commit f64ae453951cd71f5ea42329fa2a91ff61cebff0.
Revert "Revert "Began with splitting up Handler.cpp""

This reverts commit bbfce6101af1faf17462a4f788360c81f6a26f15.