[NEW] #6 add subsystem registry
[UPD] #6 cleanup comments
[UPD] #6 move fatalError to global func
[NEW] #6 add input system

- Input management system
- Windows implementation of input driver
[NEW] #6 add session subsystem

- Client subsystems initializes in session
- Subsystems creation/destroy moved to init/shutdown
- Updated log messages in subsystems
- Game loop moved to session
- Platform event polling moved to input system

close #6