Added some math functions and some effects for drawing beam boxes

math.inc: Added Math_MakeVector - Helps in filling a vector without a messy code
math.inc: Added Math_RotateVector - Rotates a vector around its zero vector
entity.inc: Added Entity_FindByPosition - Finds an entity by the given position
effects.inc: Added Effect_DrawBeamBoxRotatable* - Does the same as Effect_DrawBeamBox but with rotations
effects.inc: Added Effect_DrawAxisOfRotation* - Draws the axis of rotation at the given position and angles