better damage feedback

[Thyrexx]

We need better an more feedback for the player when he receives damage.

• red flash at the screen border
• screenshake
• ...

also better poisoned feedback:

• more green tint
• green flash at screen border
• ...

[Jakllp]

Decided on:

• Red "flash" around the screen for damage
• Potentially Screen-Shake (testing)
• Try Green around the screen whilst poisoned

[Jakllp]

Might need some adjustments but the functionality is there