Add sanity check for weapon damage in item description.

GetMinDamageWithOwnerStats and GetMaxDamageWithOwnerStats now check if the owner of the weapon is $ before checking class. This prevents an error being logged if a weapon description is checked from a vault, chest or NPC inventory. I've also cleaned up the whitespace and grammar for the whole of weapon.kod; future pull requesters for this milestone (1.0.1.3 hotfix), please contact me if you wish to edit weapon.kod.