This function calculates and returns the percent value chance to successfully
refine the item found in the specified equipment slot of the invoking character
by +1. The actual formula is beyond the scope of this document, however, it is
calculated as if the character was a blacksmith trying to refine this particular
weapon, and depends on lots and lots of stuff. For a list of equipment slots see
'getequipid'.

These values can be displayed for the player to see, or used to calculate the
random change of a refine succeeding or failing and then going through with it
(which is what the official NPC refinery scripts use it for)

// This will find a random number from 0 - 99 and if that is equal to or more
// than the value recoverd by this command it will go to L_Fail
if (getequippercentrefinery(3)<=rand(100)) goto L_Fail;