KF2HUD Optional (Selectable via ScrN Features)

[poosh]

• Made KF2HUD optional. Each player can select between Classic/Cool/KF2 HUD via ScrN Features GUI. Same with KF2 player bars.
• Both settings are separate. For example, the player can choose KF2HUD with Classic bars, or Classic HUD with KF2 bars.
• Kill/Damage messages are always in KF2 style no matter of HUD settings. They look better than the classic ones and visually fit in all HUD styles.
• Mut is ported to ScrnMutator since there is dependancy on ScrnShared anyway
• MUTATE VERSION shows the version of KF2HUD too

[poosh]

The proper way to implement the solution is refactoring ScrnHUD by adding delegate functions that custom HUD (like KF2HUD) can substitute instead of putting the check at the start of each function. But that's another story ;)

[Shtoyan]

Thanks for changes!