Bloody update:

-----WORK IN PROGRESS-----
- Now BasicEnemy bleeds on weapon contact (need to be adjusted to "On Hit" action, when implemented).
- Added tag "Weapon". Now every object tagged as Weapon makes an enemy bleed (this also will be improved in the future).
- Added splatter material, prefab and scripts related to the bleeding stuff.

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-Minor fixes.
-Solved bug in Inventory caused because Player was able to interact with an object even when it was deactivated from current scene.
-Added _inUsage variable to IPickable interface, just for preventive reasons so functions cannot be called more than a time per frame.