Added skills to the inventory items that can be used in battle.
Some skills can be obtained randomly by just finding weapons in level drops.
There are 2 tipes of skills: Active / Passive.
-Active: This kind of skill can be used anytime you want, just by pressing the
corresponding key there are for the skills. (Q, W, E, R, T)
-Passive: This skills are used automatically, by a porcent chance or just granting
some stat bonuses.